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2 daysserial: imx: serialize imx_uart_ports[] lifetimeKarl Mehltretter
commit 8b0b29fdcb47907ae0296b8fe829e918e05e300f upstream. imx_uart_probe() publishes its devm-allocated port in imx_uart_ports[] before uart_add_one_port() because console setup uses the table. The entry is not cleared when adding the port fails or after removal, leaving a dangling pointer. A sibling probe can register the shared console through that stale entry. This was reproduced under KASAN on QEMU mcimx6ul-evk by unbinding a sibling UART, unbinding the console UART and rebinding the sibling. Keep the entry valid through uart_remove_one_port(), then clear it. Protect port addition and removal together with their table updates so sibling operations cannot interleave. Reject an occupied slot rather than clobbering an active port during a duplicate-line probe. Fixes: dbff4e9ea2e8 ("IMX UART: remove statically initialized tables") Fixes: 9f322ad064f9 ("imx: serial: handle initialisation failure correctly") Reported-by: Sashiko <sashiko-bot@kernel.org> Link: https://lore.kernel.org/all/20260719162850.043B41F000E9@smtp.kernel.org Link: https://lore.kernel.org/all/20260719222501.CB4CB1F000E9@smtp.kernel.org Cc: stable@vger.kernel.org Assisted-by: Claude:claude-fable-5 Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com> Reviewed-by: Frank Li <Frank.Li@nxp.com> Link: https://patch.msgid.link/20260731181844.11330-6-kmehltretter@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
14 daysserial: sc16is7xx: enable THRI before filling TX FIFOLuca Fresi
[ Upstream commit 246ac114f485c2affb454240f3ea4fabfce22456 ] sc16is7xx_handle_tx() currently requests the THRI enable only after it has filled the TX FIFO. The request is asynchronous because the IER update is performed later by reg_work. The SC16IS7xx generates a THRI interrupt when the TX FIFO crosses its trigger level. If the FIFO drains past that level before reg_work enables THRI, the chip does not generate a new interrupt. Characters remain queued indefinitely even though the hardware FIFO is empty. This was observed on an SC16IS752 while both UART channels were active. During the stall the software TX buffer remained non-empty while TXLVL reported 64 bytes free, LSR reported THR and transmitter empty, IER had THRI enabled, and IIR reported no interrupt pending. Enable THRI synchronously before filling the FIFO so the threshold crossing cannot be missed. Fixes: cc4c1d05eb10 ("sc16is7xx: Properly resume TX after stop") Cc: stable <stable@kernel.org> Signed-off-by: Luca Fresi <luca.fresi@bithiatec.com> Link: https://patch.msgid.link/20260721222404.204746-1-luca.fresi@bithiatec.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
14 daysserial: sc16is7xx: use guards for simple mutex locksHugo Villeneuve
[ Upstream commit 0f4f88bfd7e7bf3f3293045fffdc63586b0a889f ] Guards can help to make the code more readable, so use them wherever they do so. In sc16is7xx_port_irq(), labels and 'rc' locals are eliminated completely. Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com> Link: https://patch.msgid.link/20251027142957.1032073-6-hugo@hugovil.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Stable-dep-of: 246ac114f485 ("serial: sc16is7xx: enable THRI before filling TX FIFO") Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
14 daysserial: sc16is7xx: rename EFR mutex with generic nameHugo Villeneuve
[ Upstream commit d9b2d7ddbb973b981c20b21e9228581bb156f66f ] This mutex is used as a lock when accessing registers that share the same address space, not necessarily EFR registers. For example, address 0x06 is shared by MSR, TCR and XOFF1 registers, independently of EFR. Rename the mutex with a more generic name to avoid misinterpreting its usage. Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com> Link: https://patch.msgid.link/20251027142957.1032073-3-hugo@hugovil.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Stable-dep-of: 246ac114f485 ("serial: sc16is7xx: enable THRI before filling TX FIFO") Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-08-19serial: amba-pl011: synchronize DMA teardownFan Wu
commit 440915499231e9db1c361aa45bb702e8fd3b4a32 upstream. dmaengine_terminate_all() does not wait for a running callback, so the TX callback can still touch the TX buffer after it is freed. The RX poll timer reads the RX buffers without the port lock. Switch to dmaengine_terminate_sync() and delete the RX timer before freeing the buffers. Fixes: ead76f329f77 ("ARM: 6763/1: pl011: add optional RX DMA to PL011 v2") Cc: stable <stable@kernel.org> Assisted-by: Codex:gpt-5.6 Signed-off-by: Fan Wu <fanwu01@zju.edu.cn> Link: https://patch.msgid.link/20260731085915.326775-4-fanwu01@zju.edu.cn Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-08-19serial: amba-pl011: cancel RS485 hrtimers after freeing IRQFan Wu
commit 36672c8d7d14e9c43287528455d2c97b526ea6ad upstream. The RS485 trigger hrtimers are embedded in the devm-managed port and can fire after it is freed. The IRQ handler can arm a timer, so free the IRQ first and then cancel both timers. Complete the RS485 stop without arming a timer, and cancel the timers in remove() for the suspend-then-unbind path, where shutdown is not called. This issue was found by an in-house static analysis tool. Fixes: 2c1fd53af21b ("serial: amba-pl011: Fix RTS handling in RS485 mode") Cc: stable <stable@kernel.org> Assisted-by: Codex:gpt-5.6 Signed-off-by: Fan Wu <fanwu01@zju.edu.cn> Link: https://patch.msgid.link/20260731085915.326775-3-fanwu01@zju.edu.cn Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-08-19serial: amba-pl011: fix indefinite RS485 post-send delayFan Wu
commit dcb2f7576ce460eb4f6b9048b7c266c8da5848a8 upstream. The RS485 stop hrtimer is used both to drain the transmitter and to wait out delay_rts_after_send. The callback cannot tell the two apart, so it restarts the post-send delay on every expiry and the timer never stops. Add a WAIT_AFTER_SEND_DELAY state so its expiry ends the stop sequence instead of restarting the delay. Fixes: 2c1fd53af21b ("serial: amba-pl011: Fix RTS handling in RS485 mode") Cc: stable <stable@kernel.org> Assisted-by: Codex:gpt-5.6 Signed-off-by: Fan Wu <fanwu01@zju.edu.cn> Link: https://patch.msgid.link/20260731085915.326775-2-fanwu01@zju.edu.cn Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-08-19serial: 8250_of: clear stuck empty-FIFO RX-timeout on LPC32xxRyan Wilbur
commit 1423415471274abda87024967d7fe2206ceee0ea upstream. The NXP LPC32xx UART (PORT_LPC3220) can latch an RX character-timeout interrupt while the RX FIFO is empty: IIR reports UART_IIR_RX_TIMEOUT (0x0c) but LSR.DR is clear. A character timeout is only cleared by reading RHR, but serial8250_rx_chars() reads RHR only when LSR.DR is set, so nothing ever clears the condition. The interrupt is level-triggered and re-fires immediately, so on a single-core ARM926 the resulting interrupt storm livelocks the CPU. It is reproducible when userspace repeatedly opens the front-panel port (ttyS1): serial8250_do_set_termios() re-enables interrupts on unlock and the handler then spins forever with iir=0xcc lsr=0x60 ier=0x05, tripping the soft-lockup detector in serial8250_handle_irq_locked(). LPC32xx has no dedicated 8250 glue driver, it's driven by the generic 8250_of. Add a hardware specific handle_irq for PORT_LPC3220, wired up in of_platform_serial_setup() the same way fsl8250_handle_irq is installed. The handler follows dw8250_handle_irq(): on an RX timeout with an empty FIFO (LSR.DR and LSR.BI clear) it does one throwaway RHR read to clear the condition, then calls serial8250_handle_irq_locked(). No real received data is ever discarded, and it is a no-op on healthy UARTs which never report a timeout with DR clear. This is the same class of bug already worked around in other 8250 drivers; see commit 424d79183af0 ("serial: 8250_dw: Avoid "too much work" from bogus rx timeout interrupt") which reports the identical iir=0xcc/lsr=0x60. See also UART_RX_TIMEOUT_QUIRK in 8250_omap, and the note in 8250_bcm7271. Cc: stable <stable@kernel.org> Assisted-by: Claude:Opus4.8 Signed-off-by: Ryan Wilbur <rwilbur633@gmail.com> Link: https://patch.msgid.link/20260730193920.28954-1-rwilbur633@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-08-19serial: 8250_dma: Clear stale RX state on shutdownCunhao Lu
commit e2fe6a0efecbef00e3ecc2db64dd5afa8c212b41 upstream. serial8250_release_dma() terminates RX DMA and releases the channel, but leaves rx_running set. If the port is closed while an RX transfer is active, the stale state remains while rxchan is NULL until the channel is requested again on the next open. The DesignWare BUSY workaround added by commit a7b9ce39fbe4 ("serial: 8250_dw: Ensure BUSY is deasserted") calls serial8250_rx_dma_flush() from the LCR write path during startup. This happens before serial8250_request_dma() obtains a new RX channel. On reopen, the stale rx_running state therefore makes the flush path pass a NULL channel to dmaengine_pause(), causing a kernel Oops. Clear rx_running after terminating RX DMA, matching the TX cleanup. Also make the flush helper return if the DMA object or RX channel is not available so startup and teardown paths cannot pass a NULL channel to the DMAengine API. Fixes: 0fcb7901f9d6 ("tty: serial: 8250_dma: keep own book keeping about RX transfers") Cc: stable <stable@kernel.org> Signed-off-by: Cunhao Lu <1579567540@qq.com> Link: https://patch.msgid.link/tencent_9EE2945F4C933B4D810C73C2D7485E000F06@qq.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-08-19serial: qcom-geni: fix TX DMA buffer flushJan Sebastian Götte
commit e3c04834ae1ab5e9cfbe8ac54ec734aa4774249d upstream. When transmit flushing a qcom-geni UART during an ongoing TX DMA, the UART gets stuck infinitely repeating corrupted TX DMA frames. The DMA-mode uart_ops does not provide a flush_buffer callback, so an in-flight transfer can complete after serial core has reset the transmit kfifo, underflowing its length and resubmitting page-sized transfers indefinitely. Add one that stops the transfer and clears tx_remaining and tx_queued. The stop path was also broken: it unmapped the buffer while the serial engine could still read it, and never reset the TX DMA state machine. Cancel the main sequencer command first, then reset the state machine and wait for it before unmapping. Drop the early return so a pending mapping is also cleaned up when the main command is inactive. The bug can be triggered from userspace with a large write immediately followed by TCOFLUSH. A following tcdrain will hang forever. The bug was reproduced and this fix was validated on Arduino Uno Q (QRB2210) using /dev/ttyHS1. Assisted-by: Claude:claude-5-opus Codex:gpt-5 Signed-off-by: Jan Sebastian Götte <linux@jaseg.de> Fixes: 2aaa43c70778 ("tty: serial: qcom-geni-serial: add support for serial engine DMA") Cc: stable <stable@kernel.org> Reviewed-by: Praveen Talari <praveen.talari@oss.qualcomm.com> Link: https://patch.msgid.link/20260729174105.21838-2-git@jaseg.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-08-19vt: stabilize tty reference in kbd_keycode with tty_port_tty_getJoshua Rogers
commit e25d47a526939ad44b75f778b8a7500562b84fc1 upstream. kbd_keycode() reads vc->port.tty without acquiring a tty reference, racing against con_shutdown() which clears port.tty under a different lock. Use tty_port_tty_get()/tty_kref_put() to hold a proper reference for the duration the tty pointer is needed. Assisted-by: AISLE:Snapshot Signed-off-by: Joshua Rogers <linux@joshua.hu> Cc: stable <stable@kernel.org> Link: https://patch.msgid.link/20260731-tty-vt-stuff-v1-1-be99b9da8e30@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-08-19vt: add permission check for KDSKBMETA ioctlJoshua Rogers
commit a7ad0034453ba4c353f9b8f810ee2569de33d283 upstream. KDSKBMETA modifies keyboard meta mode but lacks the !perm check that all other keyboard setter ioctls in vt_k_ioctl() enforce, allowing a process to change meta mode on a non-controlling console without authorization. Assisted-by: AISLE:Snapshot Cc: stable <stable@kernel.org> Signed-off-by: Joshua Rogers <linux@joshua.hu> Link: https://patch.msgid.link/20260731-tty-vt-stuff-v1-2-be99b9da8e30@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-08-03serial: 8250_mid: Fix NULL function pointer dereference on DNV/ICX-D/SNR ↵Jiangshan Yi
platforms commit 7fb13fd7e9a59a37cd911efff83abe19e3ee029d upstream. Commit b1b4efea05a5 ("serial: 8250_mid: Disable DMA for selected platforms") replaced the dnv_board setup and exit callbacks with PTR_IF(false, ...), which evaluates to NULL. However, the three call sites in mid8250_probe() and mid8250_remove() unconditionally dereference these function pointers without NULL checks, causing a NULL pointer dereference (kernel oops) on any Denverton (DNV), Ice Lake Xeon D (ICX-D/CDF), or Snowridge (SNR) platform. Fix this by adding the missing NULL checks before calling the setup and exit callbacks. Fixes: b1b4efea05a5 ("serial: 8250_mid: Disable DMA for selected platforms") Cc: stable <stable@kernel.org> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Jiangshan Yi <yijiangshan@kylinos.cn> Link: https://patch.msgid.link/20260715073546.1875083-1-yijiangshan@kylinos.cn Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-08-03serial: sc16is7xx: implement gpio get_direction() callbackHugo Villeneuve
commit af071d9e07e57cfff239e8d09d2f3b05ebc9c667 upstream. It's strongly recommended for GPIO drivers to always implement the .get_direction() callback - even when the direction is tracked in software. The GPIO core emits a warning when the callback is missing and a user reads the direction of a line, e.g. via /sys/kernel/debug/gpio. Fixes: dfeae619d781 ("serial: sc16is7xx") Cc: stable <stable@kernel.org> Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com> Acked-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com> Link: https://patch.msgid.link/20260716210813.2582826-1-hugo@hugovil.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-07-24serial: 8250_omap: clear rx_running on zero-length DMA completesMatthias Feser
commit 061b627ba534230a18ec4d7251562af12325d06a upstream. On AM33xx RX DMA only triggers when the FIFO reaches the configured threshold (typically 48 bytes). For smaller bursts no DMA request is issued and the FIFO is drained by RX timeout. In this case __dma_rx_do_complete() can legitimately see count == 0. The current code exits early in this case and does not clear dma->rx_running, leaving the DMA state inconsistent. This can prevent RX DMA from restarting and may cause omap_8250_rx_dma_flush() to fail, marking DMA as broken. Fix this by clearing dma->rx_running once the DMA transfer has completed or been terminated, even if no data was transferred. Fixes: a5fd8945a478 ("serial: 8250: 8250_omap.c: Clear DMA RX running status only after DMA termination is done") Cc: stable <stable@kernel.org> Signed-off-by: Matthias Feser <mfe@KBSgmbhfr.onmicrosoft.com> Reviewed-by: Moteen Shah <m-shah@ti.com> Link: https://patch.msgid.link/BE3P281MB55155F2F5795E411F5A65282EE0B2@BE3P281MB5515.DEUP281.PROD.OUTLOOK.COM Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-07-24serial: max310x: implement gpio_chip::get_direction()Tapio Reijonen
commit a483b1a91b33b7533280e7c3efd2bc1275caef18 upstream. It's strongly recommended for GPIO drivers to always implement the .get_direction() callback - even when the direction is tracked in software. The GPIO core emits a warning when the callback is missing and a user reads the direction of a line, e.g. via /sys/kernel/debug/gpio. The MAX310X keeps the GPIO direction in the GPIOCFG register (a set bit selects output), which the existing direction_input/output callbacks already program, so the current direction can be read back directly. Fixes: f65444187a66 ("serial: New serial driver MAX310X") Cc: stable <stable@kernel.org> Signed-off-by: Tapio Reijonen <tapio.reijonen@vaisala.com> Reviewed-by: Linus Walleij <linusw@kernel.org> Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com> Reviewed-by: Hugo Villeneuve <hvilleneuve@dimonoff.com> Link: https://patch.msgid.link/20260615-b4-serial-max310x-gpio-get-direction-v2-1-4704ba2b181a@vaisala.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-07-24serial: msm: Disable DMA for kernel console UARTStephan Gerhold
commit 22dd2777e6c180e1c945b00f6d18550979436324 upstream. At the moment, concurrent writes from userspace and the kernel to the console can trigger a race condition that results in an infinite loop of the same messages printed over and over again. This is most likely to happen during system startup or shutdown when the init system starts/stops a large number of system services that interact with various kernel code. When userspace writes to the TTY device, the driver initiates an asynchronous DMA transfer and releases the port lock. At the same moment, the kernel printk path might grab the port lock and re-configure the UART controller for PIO, without waiting for the DMA operation to complete. It seems like this collision results in zero progress being reported for the DMA engine, so the same text is printed to the console over and over again. For the kernel console, we want a reliable output path that will be functional even during crashes etc. So rather than implementing complex code to synchronize the kernel console write routines with the userspace DMA write routines, simply disable DMA for the console UART instance. Similar checks exist in many other serial drivers, e.g. 8250_port.c, imx.c, sh-sci.c etc. Cc: stable <stable@kernel.org> Fixes: 3a878c430fd6 ("tty: serial: msm: Add TX DMA support") Signed-off-by: Stephan Gerhold <stephan.gerhold@linaro.org> Acked-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com> Link: https://patch.msgid.link/20260706-serial-msm-console-dma-collision-v1-1-3179b8cb1d89@linaro.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-07-18serial: 8250_mid: Disable DMA for selected platformsAndy Shevchenko
commit b1b4efea05a56c0995e4702a86d6624b4fdff32f upstream. In accordance with Errata (specification updates) HSUART May Stop Functioning when DMA is Active. - Denverton document #572409, rev 3.4, DNV60 - Ice Lake Xeon D document #714070, ICXD65 - Snowridge document #731931, SNR44 For a quick fix just disable the respective callbacks during the device probe. Depending on the future development we might remove them completely. Reported-by: micas-opensource <zjianan156@gmail.com> Closes: https://lore.kernel.org/linux-serial/20250625031409.2404219-1-opensource@ruijie.com.cn/ Fixes: 6ede6dcd87aa ("serial: 8250_mid: add support for DMA engine handling from UART MMIO") Cc: stable <stable@kernel.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://patch.msgid.link/20260626094937.561776-1-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-07-04serial: 8250_dw: unregister 8250 port if clk_notifier_register() failsStepan Ionichev
commit 10fc708b4de7f86002d2d735a2dbf3b5b7f65692 upstream. dw8250_probe() registers the 8250 port via serial8250_register_8250_port() and then, if the device has a clock, registers a clock notifier. If clk_notifier_register() fails, probe returns the error but leaves the 8250 port registered. The matching serial8250_unregister_port() lives in dw8250_remove(), which is not called when probe fails, so the port slot stays occupied until the device is rebound or the system is rebooted. The devm-allocated driver data is freed while the port still references it (via the saved private_data and serial_in/serial_out callbacks), so any access to that port slot before a rebind is a use-after-free hazard. Unregister the port on the clk_notifier_register() error path. Fixes: cc816969d7b5 ("serial: 8250_dw: Fix common clocks usage race condition") Cc: stable@vger.kernel.org Signed-off-by: Stepan Ionichev <sozdayvek@gmail.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://patch.msgid.link/20260514143746.23671-2-sozdayvek@gmail.com Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-06-27serial: qcom_geni: Fix RX DMA stall when SE_DMA_RX_LEN_IN is zeroViken Dadhaniya
commit b93062b6d8a1b2d9bad235cac25558a909819026 upstream. In qcom_geni_serial_handle_rx_dma(), geni_se_rx_dma_unprep() clears port->rx_dma_addr before SE_DMA_RX_LEN_IN is read. If the register is zero, for example when the RX stale counter fires on an idle line, the handler returns without calling geni_se_rx_dma_prep(). The next RX DMA interrupt then hits the !port->rx_dma_addr guard and returns immediately, so the RX DMA buffer is never rearmed and later input is lost. Keep the handler on the rearm path when rx_in is zero. Warn about the unexpected zero-length DMA completion, skip received-data handling, and always call geni_se_rx_dma_prep(). Fixes: 2aaa43c70778 ("tty: serial: qcom-geni-serial: add support for serial engine DMA") Cc: stable@vger.kernel.org Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com> Signed-off-by: Viken Dadhaniya <viken.dadhaniya@oss.qualcomm.com> Link: https://patch.msgid.link/20260528-serial-rx-0-byte-fix-v2-1-b4195cfe342f@oss.qualcomm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-06-27vc_screen: fix null-ptr-deref in vcs_notifier() during concurrent vcs_writeYi Yang
commit a287620312dc6dcb9a093417a0e589bf30fcf38a upstream. A KASAN null-ptr-deref was observed in vcs_notifier(): BUG: KASAN: null-ptr-deref in vcs_notifier+0x98/0x130 Read of size 2 at addr qmp_cmd_name: qmp_capabilities, arguments: {} The issue is a race condition in vcs_write(). When the console_lock is temporarily dropped (to copy data from userspace), the vc_data pointer obtained from vcs_vc() may become stale. After re-acquiring the lock, vcs_vc() is called again to re-validate the pointer. If the vc has been deallocated in the meantime, vcs_vc() returns NULL, and the while loop breaks (with written > 0). However, after the loop, vcs_scr_updated(vc) is still called with the now-NULL vc pointer, leading to a null pointer dereference in the notifier chain (vcs_notifier dereferences param->vc). Fix this by adding a NULL check for vc before calling vcs_scr_updated(). Fixes: 8fb9ea65c9d1 ("vc_screen: reload load of struct vc_data pointer in vcs_write() to avoid UAF") Cc: stable@vger.kernel.org Signed-off-by: Yi Yang <yiyang13@huawei.com> Reviewed-by: Jiri Slaby <jirislaby@kernel.org> Link: https://patch.msgid.link/20260604060734.2914976-1-yiyang13@huawei.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-06-09serdev: Provide a bustype shutdown functionUwe Kleine-König
[ Upstream commit 6d71c62b13c33ea858ab298fe20beaec5736edc7 ] To prepare serdev driver to migrate away from struct device_driver::shutdown (and then eventually remove that callback) create a serdev driver shutdown callback and migration code to keep the existing behaviour. Note this introduces a warning for each driver at register time that isn't converted yet to that callback. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com> Link: https://patch.msgid.link/ab518883e3ed0976a19cb5b5b5faf42bd3a655b7.1765526117.git.u.kleine-koenig@baylibre.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Stable-dep-of: 375ba7484132 ("Bluetooth: hci_qca: Convert timeout from jiffies to ms") Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-06-09serial: 8250_dw: dispatch SysRq character in dw8250_handle_irq()Jacques Nilo
commit 2e211723953f7740e54b53f3d3a0d5e351a5e223 upstream. dw8250_handle_irq() calls serial8250_handle_irq_locked() with the port lock held via guard(uart_port_lock_irqsave). The guard destructor is plain uart_port_unlock_irqrestore(), so a SysRq character captured into port->sysrq_ch by uart_prepare_sysrq_char() is dropped without ever being dispatched to handle_sysrq(). This is the same regression pattern as in serial8250_handle_irq(), introduced when 883c5a2bc934 ("serial: 8250_dw: Rework dw8250_handle_irq() locking and IIR handling") moved the function to the guard()-based locking scheme without using the sysrq-aware unlock helper. Switch to guard(uart_port_lock_check_sysrq_irqsave) so that captured sysrq_ch is dispatched on scope exit, matching the fix in serial8250_handle_irq(). Fixes: 883c5a2bc934 ("serial: 8250_dw: Rework dw8250_handle_irq() locking and IIR handling") Cc: stable@vger.kernel.org Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Signed-off-by: Jacques Nilo <jnilo@free.fr> Link: https://patch.msgid.link/ed56fcaf4af24e4ed011a7bce206e0182acb761c.1778675349.git.jnilo@free.fr Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-06-09serial: 8250: dispatch SysRq character in serial8250_handle_irq()Jacques Nilo
commit 71f42b2149a1307a97165b409493665579462ea0 upstream. serial8250_handle_irq() captures a SysRq character into port->sysrq_ch inside serial8250_handle_irq_locked() via uart_prepare_sysrq_char() (reached from serial8250_read_char()). Dispatch of that captured character to handle_sysrq() is expected to happen at port-unlock time, through uart_unlock_and_check_sysrq[_irqrestore](). After commit 8324a54f604d ("serial: 8250: Add serial8250_handle_irq_locked()") the function was reduced to a wrapper that takes the port lock via guard(uart_port_lock_irqsave) whose destructor is plain uart_port_unlock_irqrestore(). The sysrq-aware unlock helper is no longer called, so port->sysrq_ch is captured but never dispatched: BREAK + SysRq key is consumed silently. This was the very condition Johan Hovold's 853a9ae29e978 ("serial: 8250: fix handle_irq locking", 2021) introduced uart_unlock_and_check_sysrq_irqrestore() to address. Switch to the new guard(uart_port_lock_check_sysrq_irqsave), whose destructor is the sysrq-aware unlock helper, restoring the pre-split behaviour. Update the Context: comment on serial8250_handle_irq_locked() so future HW-specific 8250 wrappers know to use the same guard or the explicit sysrq-aware unlock. Verified on RTL8196E with CONFIG_MAGIC_SYSRQ_SERIAL=y: BREAK + 'h' on the console UART produces the SysRq help dump in dmesg and the brk counter in /proc/tty/driver/serial increments correctly. Fixes: 8324a54f604d ("serial: 8250: Add serial8250_handle_irq_locked()") Cc: stable@vger.kernel.org Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Signed-off-by: Jacques Nilo <jnilo@free.fr> Link: https://patch.msgid.link/52692ae6c3501f7940347cef364ad7fcacaab7e5.1778675349.git.jnilo@free.fr Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-06-09serial: zs: Convert to use a platform deviceMaciej W. Rozycki
commit 7cac59d08a73cb866ec51a483a6f3fe0f531947c upstream. Prevent a crash from happening as the first serial port is initialised: Console: switching to mono frame buffer device 160x64 fb0: PMAG-AA frame buffer device at tc0 DECstation Z85C30 serial driver version 0.10 CPU 0 Unable to handle kernel paging request at virtual address 0000002c, epc == 803ab00c, ra == 803aafe0 Oops[#1]: CPU: 0 PID: 1 Comm: swapper Not tainted 6.4.0-rc3-00031-g84a9582fd203-dirty #57 $ 0 : 00000000 10012c00 803aaeb0 00000000 $ 4 : 80e12f60 80e12f50 80e12f58 81000030 $ 8 : 00000000 805ff37c 00000000 33433538 $12 : 65732030 00000006 80c2915d 6c616972 $16 : 80e12f00 807b7630 00000000 00000000 $20 : 00000004 00000348 000001a0 807623b8 $24 : 00000018 00000000 $28 : 80c24000 80c25d60 8078b148 803aafe0 Hi : 00000000 Lo : 00000000 epc : 803ab00c serial_base_ctrl_add+0x78/0xf4 ra : 803aafe0 serial_base_ctrl_add+0x4c/0xf4 Status: 10012c03 KERNEL EXL IE Cause : 00000008 (ExcCode 02) BadVA : 0000002c PrId : 00000440 (R4400SC) Modules linked in: Process swapper (pid: 1, threadinfo=(ptrval), task=(ptrval), tls=00000000) Stack : 80760000 00000cc0 00400044 00400040 803aa02c 80d61ab8 00000000 807b7630 80760000 807623b8 807b7628 803aa644 80386998 00000000 80e17780 80220f68 80e17780 80d61ab8 80c17d80 80e17780 80e17780 8063c798 80e17780 80383fa0 00000010 80e17780 00000000 80386998 807a0000 00000000 00400040 8038f848 807623b8 80d61ab8 00000004 80e17780 00000000 803a68e4 80c25e2c 803bb884 ... Call Trace: [<803ab00c>] serial_base_ctrl_add+0x78/0xf4 [<803aa644>] serial_core_register_port+0x174/0x69c [<8077e9ac>] zs_init+0xc8/0xfc [<800404d4>] do_one_initcall+0x40/0x2ac [<8076cecc>] kernel_init_freeable+0x1e4/0x270 [<80605bec>] kernel_init+0x20/0x108 [<800431e8>] ret_from_kernel_thread+0x14/0x1c Code: 2442aeb0 ae120024 ae0200d0 <8c67002c> 50e00001 8c670000 3c06806e 3c05806e afb30010 ---[ end trace 0000000000000000 ]--- (report at the offending commit) -- where a pointer is dereferenced that has been derived from a null pointer to the port's parent device. Since no device is available with legacy probing and it's not anymore a preferable way to discover devices anyway, switch the driver to using a platform device and use it as the port's parent device. Update resource handling accordingly and only request the actual span of addresses used within the slot, which will have had its resource already requested by generic platform device code. Use platform_driver_probe() not just because SCC devices are fixed with solder on board and not straightforward to remove, but foremost because the associated TTY's major device number is the same as used by the dz driver and the first driver to claim it will prevent the other one from using it. Either one DZ device or some SCC devices will be present in a given system but never both at a time, and therefore we want the major device number to be claimed by the first driver to actually successfully bind to its device and platform_driver_probe() is a way to fulfil that. An unfortunate consequence of the switch to a platform device is we now hand the console over from the bootconsole much later in the bootstrap. The firmware console handler appears good enough though to work so late and in particular with interrupts enabled. Since there is one way only remaining to reach zs_reset() now, remove the port initialisation marker as no longer needed and go through the channel reset unconditionally. Fixes: 84a9582fd203 ("serial: core: Start managing serial controllers to enable runtime PM") Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk> Cc: stable@vger.kernel.org # needs to use .remove_new for <= 6.10 Link: https://patch.msgid.link/alpine.DEB.2.21.2605062328480.46195@angie.orcam.me.uk Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-06-09serial: zs: Switch to using channel resetMaciej W. Rozycki
commit 8572955630f30948837088aa98bcbe0532d1ceac upstream. Switch the driver to using the channel reset rather than hardware reset, simplifying handling by removing an interference between channels that causes the other channel to become uninitialised afterwards. There is little difference between the two kinds of reset in terms of register settings that result, and we initialise the whole register set right away anyway. However this prevents a hang from happening should the console output handler in the firmware try to access the other port whose transmitter has been disabled and line parameters messed up. For example this will happen if the keyboard port (port A) is chosen for the system console, unusually but not insanely for a headless system, as the port is wired to a standard DA-15 connector and an adapter can be easily made. Or with the next change in place this would happen for the regular console port (port B), since the keyboard port (port A) will be initialised first. Just remove the unnecessary complication then, a channel reset is good enough. We still need the initialisation marker, now per channel rather than per SCC, as for the console port zs_reset() will be called twice: once early on via zs_serial_console_init() for the console setup only, and then again via zs_config_port() as the port is associated with a TTY device. Fixes: 8b4a40809e53 ("zs: move to the serial subsystem") Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk> Cc: stable@vger.kernel.org # v2.6.23+ Link: https://patch.msgid.link/alpine.DEB.2.21.2605062323430.46195@angie.orcam.me.uk Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-06-09serial: zs: Fix bootconsole handover lockupMaciej W. Rozycki
commit 6c05cf72e13314ce9b770b5951695dc5a2152920 upstream. Calling zs_reset() in the course of setting up the serial device causes line parameters to be reset and the transmitter disabled. We've been lucky in that no message is usually produced to the kernel log between this call and the later call to uart_set_options() in the course of console setup done by zs_serial_console_init(), or the system would hang as the console output handler in the firmware tried to access a port the transmitter of which has been disabled and line parameters messed up. This will change with the next change to the driver, so fix zs_reset() such that line parameters are set for 9600n8 console operation as with the system firmware and the transmitter re-enabled after reset. This also means zs_pm() serves no purpose anymore, so drop it. Fixes: 8b4a40809e53 ("zs: move to the serial subsystem") Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk> Cc: stable@vger.kernel.org # v2.6.23+ Link: https://patch.msgid.link/alpine.DEB.2.21.2605062308040.46195@angie.orcam.me.uk Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-06-09serial: dz: Convert to use a platform deviceMaciej W. Rozycki
commit 5d7a49d60b8fda66da60e240fd7315232fa1754f upstream. Prevent a crash from happening as the first serial port is initialised: Console: switching to colour frame buffer device 160x64 tgafb: SFB+ detected, rev=0x02 fb0: Digital ZLX-E1 frame buffer device at 0x1e000000 DECstation DZ serial driver version 1.04 CPU 0 Unable to handle kernel paging request at virtual address 000000bc, epc == 8048b3a4, ra == 80470a78 Oops[#1]: CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.19.0-dirty #35 NONE $ 0 : 00000000 1000ac00 00000004 804707ac $ 4 : 00000000 80e20850 80e20858 81000030 $ 8 : 00000000 8072c81c 00000008 fefefeff $12 : 6c616972 00000006 80c5917f 69726420 $16 : 80e20800 00000000 808f8968 80e20800 $20 : 00000000 807f5a90 808b0094 808d3bc8 $24 : 00000018 80479030 $28 : 80c2e000 80c2fd70 00000069 80470a78 Hi : 00000004 Lo : 00000000 epc : 8048b3a4 __dev_fwnode+0x0/0xc ra : 80470a78 serial_base_ctrl_add+0xa0/0x168 Status: 1000ac04 IEp Cause : 30000008 (ExcCode 02) BadVA : 000000bc PrId : 00000220 (R3000) Modules linked in: Process swapper/0 (pid: 1, threadinfo=(ptrval), task=(ptrval), tls=00000000) Stack : 00400044 00400040 8046f4cc 00000000 808a6148 808a0000 808f8968 8086983c 808e0000 8046fc84 1000ac01 00000028 80e20700 802ba3f8 80e20700 80d34a94 80c1b900 80e20700 80e20700 80e20700 80e20700 80444650 00000000 00000000 00000000 807f5a90 808b0094 80447080 00400040 808e0000 80d34a94 808a6148 80d34a94 00000004 80e20700 00000000 8076974c 80469810 80c2fe3c 1000ac01 ... Call Trace: [<8048b3a4>] __dev_fwnode+0x0/0xc [<80470a78>] serial_base_ctrl_add+0xa0/0x168 [<8046fc84>] serial_core_register_port+0x1c8/0x974 [<808c6af0>] dz_init+0x74/0xc8 [<800470e0>] do_one_initcall+0x44/0x2d4 [<808b111c>] kernel_init_freeable+0x258/0x308 [<8072e434>] kernel_init+0x20/0x114 [<80049cd0>] ret_from_kernel_thread+0x14/0x1c Code: 27bd0018 03e00008 2402ffea <8c8200bc> 03e00008 00000000 27bdffc0 afbe0038 afb30024 ---[ end trace 0000000000000000 ]--- -- where a pointer is dereferenced that has been derived from a null pointer to the port's parent device. Since no device is available with legacy probing and it's not anymore a preferable way to discover devices anyway, switch the driver to using a platform device and use it as the port's parent device. Update resource handling accordingly and only request the actual span of addresses used within the slot, which will have had its resource already requested by generic platform device code. Use platform_driver_probe() not just because the DZ device is fixed with solder on board and not straightforward to remove, but foremost because the associated TTY's major device number is the same as used by the zs driver and the first driver to claim it will prevent the other one from using it. Either one DZ device or some SCC devices will be present in a given system but never both at a time, and therefore we want the major device number to be claimed by the first driver to actually successfully bind to its device and platform_driver_probe() is a way to fulfil that. An unfortunate consequence of the switch to a platform device is we now hand the console over from the bootconsole much later in the bootstrap. The firmware console handler appears good enough though to work so late and in particular with interrupts enabled. Conversely only starting the console port so late lets the reset code fully utilise our delay handlers, so switch from udelay() to fsleep() for transmitter draining so as to avoid busy-waiting for an excessive amount of time. Fixes: 84a9582fd203 ("serial: core: Start managing serial controllers to enable runtime PM") Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk> Cc: stable@vger.kernel.org # needs to use .remove_new for <= 6.10 Link: https://patch.msgid.link/alpine.DEB.2.21.2605062326540.46195@angie.orcam.me.uk Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-06-09serial: dz: Fix bootconsole handover lockupMaciej W. Rozycki
commit 7f127b2208e5e2b817243cad41fe4211a6d5a7a3 upstream. Calling dz_reset() in the course of setting up the serial device causes line parameters to be reset and the transmitter disabled. We've been lucky in that no message is usually produced to the kernel log between this call and the later call to uart_set_options() in the course of console setup done by dz_serial_console_init(), or the system would hang as the console output handler in the firmware tried to access a port the transmitter of which has been disabled and line parameters messed up. This will change with the next change to the driver, so fix dz_reset() such that line parameters are set for 9600n8 console operation as with the system firmware and the transmitter re-enabled after reset. This also means dz_pm() serves no purpose anymore, so drop it. Fixes: e6ee512f5a77 ("dz.c: Resource management") Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk> Cc: stable@vger.kernel.org # v2.6.25+ Link: https://patch.msgid.link/alpine.DEB.2.21.2605062302010.46195@angie.orcam.me.uk Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-06-09serial: dz: Fix bootconsole message clobbering at chip resetMaciej W. Rozycki
commit ca904f4b42355287bc5ce8b7550ebe909cda4c2c upstream. In the DZ interface as implemented by the DC7085 gate array the serial transmitters are double buffered, meaning that at the time a transmitter is ready to accept the next character there is one in the transmit shift register still being sent to the line. Issuing a master clear at this time causes this character to be lost, so wait an extra amount of time sufficient for the transmit shift register to drain at 9600bps, which is the baud rate setting used by the firmware console. Mind the specified 1.4us TRDY recovery time in the course and continue using iob() as the completion barrier, since the platforms involved use a write buffer that can delay and combine writes, and reorder them with respect to reads regardless of the MMIO locations accessed and we still lack a platform-independent handler for that. When called from dz_serial_console_init() this is too early for fsleep() to work and even before lpj has been calculated and therefore the delay is actually not sufficient for the transmitter to drain and is merely a placeholder now. This will be addressed in a follow-up change. Fixes: e6ee512f5a77 ("dz.c: Resource management") Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk> Cc: stable@vger.kernel.org # v2.6.25+ Link: https://patch.msgid.link/alpine.DEB.2.21.2605062259080.46195@angie.orcam.me.uk Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-06-09serial: fsl_lpuart: fix rx buffer and DMA map leaks in start_rx_dmaShitalkumar Gandhi
commit 9a9254c4a2a3ca2b3da16d173f3b0dd01f397ff6 upstream. lpuart_start_rx_dma() allocates sport->rx_ring.buf with kzalloc() and then maps a scatterlist via dma_map_sg(). On three subsequent error paths the function returns directly without releasing those resources: - when dma_map_sg() returns 0 (-EINVAL): ring->buf is leaked. - when dmaengine_slave_config() fails: ring->buf and the DMA mapping are leaked. - when dmaengine_prep_dma_cyclic() returns NULL: ring->buf and the DMA mapping are leaked. The sole cleanup path, lpuart_dma_rx_free(), is only reached when lpuart_dma_rx_use is set, and the caller lpuart_rx_dma_startup() clears that flag on failure of lpuart_start_rx_dma(). So these resources are permanently leaked on every failure in this function. Repeated port open/close or termios changes under error conditions will slowly consume memory and leave stale streaming DMA mappings behind. Fix it by introducing two error labels that unmap the scatterlist and free the ring buffer as appropriate. While here, replace the misleading -EFAULT (bad userspace pointer) returned when dmaengine_prep_dma_cyclic() fails with the more accurate -ENOMEM, matching how other dmaengine users in the tree treat this failure. No functional change on the success path. Fixes: 5887ad43ee02 ("tty: serial: fsl_lpuart: Use cyclic DMA for Rx") Cc: stable <stable@kernel.org> Signed-off-by: Shitalkumar Gandhi <shitalkumar.gandhi@cambiumnetworks.com> Reviewed-by: Frank Li <Frank.Li@nxp.com> Link: https://patch.msgid.link/20260420135903.2062024-1-shitalkumar.gandhi@cambiumnetworks.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-06-09serial: zs: Fix swapped RI/DSR modem line transition countingMaciej W. Rozycki
commit d15cd40cb1858f75846eaafa9a6bca841b790a92 upstream. Fix a thinko in the status interrupt handler that has caused counters for the RI and DSR modem line transitions to be used for the other line each. Fixes: 8b4a40809e53 ("zs: move to the serial subsystem") Cc: stable <stable@kernel.org> Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk> Link: https://patch.msgid.link/alpine.DEB.2.21.2604101747110.29980@angie.orcam.me.uk Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-06-09serial: sh-sci: fix memory region release in error pathHongling Zeng
commit 92b1ea22454b08a39baef3a7290fb3ec50366616 upstream. The sci_request_port() function uses request_mem_region() to reserve I/O memory, but in the error path when sci_remap_port() fails, it incorrectly calls release_resource() instead of release_mem_region(). This mismatch can cause resource accounting issues. Fix it by using the correct release function, consistent with sci_release_port(). Fixes: e2651647080930a1 ("serial: sh-sci: Handle port memory region reservations.") Cc: stable <stable@kernel.org> Reported-by: kernel test robot <lkp@intel.com> Reported-by: Dan Carpenter <error27@gmail.com> Closes: https://lore.kernel.org/r/202604032356.SzEjYkBC-lkp@intel.com/ Signed-off-by: Hongling Zeng <zenghongling@kylinos.cn> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be> Link: https://patch.msgid.link/20260421065737.724187-1-zenghongling@kylinos.cn Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-06-09serial: qcom_geni: fix kfifo underflow when flush precedes DMA completion IRQViken Dadhaniya
commit 452d6fa37ae9b021f4f6d397dbae077f7296f6f4 upstream. When uart_flush_buffer() runs before the DMA completion IRQ is delivered, the following race can occur (all steps serialized by uart_port_lock): 1. DMA starts: tx_remaining = N, kfifo contains N bytes 2. DMA completes in hardware; IRQ is pending but not yet delivered 3. uart_flush_buffer() acquires the port lock and calls kfifo_reset(), making kfifo_len() = 0 while tx_remaining remains N 4. uart_flush_buffer() releases the port lock 5. DMA IRQ fires; handle_tx_dma() acquires the port lock and calls uart_xmit_advance(uport, tx_remaining) on an empty kfifo uart_xmit_advance() increments kfifo->out by tx_remaining. Since kfifo_reset() already set both in and out to 0, out wraps past in, causing kfifo_len() to return UART_XMIT_SIZE - tx_remaining. The next start_tx_dma() call then submits a DMA transfer of stale buffer data. Fix this by snapshotting kfifo_len() at the start of handle_tx_dma() and skipping uart_xmit_advance() when fifo_len < tx_remaining, which indicates the kfifo was reset by a preceding flush. Fixes: 2aaa43c70778 ("tty: serial: qcom-geni-serial: add support for serial engine DMA") Cc: stable <stable@kernel.org> Signed-off-by: Viken Dadhaniya <viken.dadhaniya@oss.qualcomm.com> Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com> Link: https://patch.msgid.link/20260506-serial-dma-stale-tx-buf-v1-1-e3ccb360d719@oss.qualcomm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-06-09serial: qcom-geni: fix UART_RX_PAR_EN bit positionPrasanna S
commit ca2584d841b69391ffc4144840563d2e1a0018df upstream. UART_RX_PAR_EN is incorrectly defined as bit 3, which triggers false framing errors (S_GP_IRQ_1_EN) and causes received data to be dropped when parity is enabled and the parity bit is 0. Define UART_RX_PAR_EN as bit 4 of the SE_UART_RX_TRANS_CFG register, as specified in the reference manual. Fixes: c4f528795d1a ("tty: serial: msm_geni_serial: Add serial driver support for GENI based QUP") Cc: stable <stable@kernel.org> Signed-off-by: Prasanna S <prasanna.s@oss.qualcomm.com> Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com> Link: https://patch.msgid.link/20260428-serial-bit-correct-v1-1-9131ad5b97d8@oss.qualcomm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-06-09serial: altera_jtaguart: handle uart_add_one_port() failuresMyeonghun Pak
commit ea66be25f0e934f49d24cd0c5845d13cdba3520b upstream. altera_jtaguart_probe() maps the register window before registering the UART port, but it ignores failures from uart_add_one_port(). If port registration fails, probe still returns success and the mapping remains live until a later remove path that is not part of probe failure cleanup. Return the uart_add_one_port() error and unmap the register window on that failure path. This issue was identified during our ongoing static-analysis research while reviewing kernel code. Fixes: 5bcd601049c6 ("serial: Add driver for the Altera JTAG UART") Cc: stable <stable@kernel.org> Co-developed-by: Ijae Kim <ae878000@gmail.com> Signed-off-by: Ijae Kim <ae878000@gmail.com> Signed-off-by: Myeonghun Pak <mhun512@gmail.com> Link: https://patch.msgid.link/20260512065837.79528-1-mhun512@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-06-09tty: serial: samsung: Remove redundant port lock acquisition in rx helpersTudor Ambarus
commit a3bb136bff5e6a5e48cdd813246c9c4686feaaa9 upstream. Sashiko identified a deadlock when the console flow is engaged [1]. When console flow control is enabled (UPF_CONS_FLOW), s3c24xx_serial_stop_tx() calls s3c24xx_serial_rx_enable() and s3c24xx_serial_start_tx() calls s3c24xx_serial_rx_disable(). The serial core framework invokes the .stop_tx() and .start_tx() callbacks with the port->lock spinlock already held. Furthermore, all internal driver paths that invoke stop_tx (such as the DMA TX completion handler s3c24xx_serial_tx_dma_complete() or the PIO TX IRQ handler s3c24xx_serial_tx_irq()) also acquire port->lock prior to calling it. (Note that s3c24xx_serial_start_tx() is only invoked by the serial core). However, s3c24xx_serial_rx_enable() and s3c24xx_serial_rx_disable() unconditionally attempt to acquire port->lock again using uart_port_lock_irqsave(). Since spinlocks are not recursive, this causes a deadlock on the same CPU when console flow control is engaged. Remove the redundant lock acquisition from both rx helper functions. Cc: stable <stable@kernel.org> Fixes: b497549a035c ("[ARM] S3C24XX: Split serial driver into core and per-cpu drivers") Reported-by: John Ogness <john.ogness@linutronix.de> Closes: https://sashiko.dev/#/patchset/20260506121606.5805-1-john.ogness%40linutronix.de [1] Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org> Link: https://patch.msgid.link/20260515-samsung-tty-flow-control-deadlock-v1-1-93255edbc9bc@linaro.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-06-09tty: serial: pch_uart: add check for dma_alloc_coherent()Zhaoyang Yu
commit 6fe472c1bbbe238e91141f7cabc1226e96a60d43 upstream. Add a check for dma_alloc_coherent() failure to prevent a potential NULL pointer dereference in dma_handle_rx(). Properly release DMA channels and the PCI device reference using a goto ladder if the allocation fails. Fixes: 3c6a483275f4 ("Serial: EG20T: add PCH_UART driver") Cc: stable <stable@kernel.org> Signed-off-by: Zhaoyang Yu <2426767509@qq.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://patch.msgid.link/tencent_E328416B7CFD436F6029F2DF02AD7ED89C08@qq.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-05-23tty: serial: ip22zilog: Fix section mispatch warningThomas Bogendoerfer
[ Upstream commit a1a81aef99e853dec84241d701fbf587d713eb5b ] ip22zilog_prepare() is now called by driver probe routine, so it shouldn't be in the __init section any longer. Fixes: 3fc36ae6abd2 ("tty: serial: ip22zilog: Use platform device for probing") Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202604020945.c9jAvCPs-lkp@intel.com/ Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de> Link: https://patch.msgid.link/20260402102154.136620-1-tbogendoerfer@suse.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2026-05-23tty: hvc_iucv: fix off-by-one in number of supported devicesRandy Dunlap
[ Upstream commit f2a880e802ad12d1e38039d1334fb1475d0f5241 ] MAX_HVC_IUCV_LINES == HVC_ALLOC_TTY_ADAPTERS == 8. This is the number of entries in: static struct hvc_iucv_private *hvc_iucv_table[MAX_HVC_IUCV_LINES]; Sometimes hvc_iucv_table[] is limited by: (a) if (num > hvc_iucv_devices) // for error detection or (b) for (i = 0; i < hvc_iucv_devices; i++) // in 2 places (so these 2 don't agree; second one appears to be correct to me.) hvc_iucv_devices can be 0..8. This is a counter. (c) if (hvc_iucv_devices > MAX_HVC_IUCV_LINES) If hvc_iucv_devices == 8, (a) allows the code to access hvc_iucv_table[8]. Oops. Fixes: 44a01d5ba8a4 ("[S390] s390/hvc_console: z/VM IUCV hypervisor console support") Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Link: https://patch.msgid.link/20260130072939.1535869-1-rdunlap@infradead.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2026-04-11vt: resize saved unicode buffer on alt screen exit after resizeNicolas Pitre
commit 3ddbea7542ae529c1a88ef9a8b1ce169126211f6 upstream. Instead of discarding the saved unicode buffer when the console was resized while in the alternate screen, resize it to the current dimensions using vc_uniscr_copy_area() to preserve its content. This properly restores the unicode screen on alt screen exit rather than lazily rebuilding it from a lossy reverse glyph translation. On allocation failure the stale buffer is freed and vc_uni_lines is set to NULL so it gets lazily rebuilt via vc_uniscr_check() when next needed. Fixes: 40014493cece ("vt: discard stale unicode buffer on alt screen exit after resize") Cc: stable <stable@kernel.org> Signed-off-by: Nicolas Pitre <nico@fluxnic.net> Link: https://patch.msgid.link/3nsr334n-079q-125n-7807-n4nq818758ns@syhkavp.arg Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-04-11vt: discard stale unicode buffer on alt screen exit after resizeLiav Mordouch
commit 40014493cece72a0be5672cd86763e53fb3ec613 upstream. When enter_alt_screen() saves vc_uni_lines into vc_saved_uni_lines and sets vc_uni_lines to NULL, a subsequent console resize via vc_do_resize() skips reallocating the unicode buffer because vc_uni_lines is NULL. However, vc_saved_uni_lines still points to the old buffer allocated for the original dimensions. When leave_alt_screen() later restores vc_saved_uni_lines, the buffer dimensions no longer match vc_rows/vc_cols. Any operation that iterates over the unicode buffer using the current dimensions (e.g. csi_J clearing the screen) will access memory out of bounds, causing a kernel oops: BUG: unable to handle page fault for address: 0x0000002000000020 RIP: 0010:csi_J+0x133/0x2d0 The faulting address 0x0000002000000020 is two adjacent u32 space characters (0x20) interpreted as a pointer, read from the row data area past the end of the 25-entry pointer array in a buffer allocated for 80x25 but accessed with 240x67 dimensions. Fix this by checking whether the console dimensions changed while in the alternate screen. If they did, free the stale saved buffer instead of restoring it. The unicode screen will be lazily rebuilt via vc_uniscr_check() when next needed. Fixes: 5eb608319bb5 ("vt: save/restore unicode screen buffer for alternate screen") Cc: stable <stable@kernel.org> Tested-by: Liav Mordouch <liavmordouch@gmail.com> Signed-off-by: Liav Mordouch <liavmordouch@gmail.com> Reviewed-by: Nicolas Pitre <nico@fluxnic.net> Link: https://patch.msgid.link/20260327170204.29706-1-liavmordouch@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-03-25serial: uartlite: fix PM runtime usage count underflow on probeMaciej Andrzejewski ICEYE
commit d54801cd509515f674a5aac1d3ea1401d2a05863 upstream. ulite_probe() calls pm_runtime_put_autosuspend() at the end of probe without holding a corresponding PM runtime reference for non-console ports. During ulite_assign(), uart_add_one_port() triggers uart_configure_port() which calls ulite_pm() via uart_change_pm(). For non-console ports, the UART core performs a balanced get/put cycle: uart_change_pm(ON) -> ulite_pm() -> pm_runtime_get_sync() +1 uart_change_pm(OFF) -> ulite_pm() -> pm_runtime_put_autosuspend() -1 This leaves no spare reference for the pm_runtime_put_autosuspend() at the end of probe. The PM runtime core prevents the count from actually going below zero, and instead triggers a "Runtime PM usage count underflow!" warning. For console ports the bug is masked: the UART core skips the uart_change_pm(OFF) call, so the UART core's unbalanced get happens to pair with probe's trailing put. Add pm_runtime_get_noresume() before pm_runtime_enable() to take an explicit probe-owned reference that the trailing pm_runtime_put_autosuspend() can release. This ensures a correct usage count regardless of whether the port is a console. Fixes: 5bbe10a6942d ("tty: serial: uartlite: Add runtime pm support") Cc: stable <stable@kernel.org> Signed-off-by: Maciej Andrzejewski ICEYE <maciej.andrzejewski@m-works.net> Link: https://patch.msgid.link/20260305123746.4152800-1-maciej.andrzejewski@m-works.net Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-03-25serial: core: fix infinite loop in handle_tx() for PORT_UNKNOWNJiayuan Chen
commit 455ce986fa356ff43a43c0d363ba95fa152f21d5 upstream. uart_write_room() and uart_write() behave inconsistently when xmit_buf is NULL (which happens for PORT_UNKNOWN ports that were never properly initialized): - uart_write_room() returns kfifo_avail() which can be > 0 - uart_write() checks xmit_buf and returns 0 if NULL This inconsistency causes an infinite loop in drivers that rely on tty_write_room() to determine if they can write: while (tty_write_room(tty) > 0) { written = tty->ops->write(...); // written is always 0, loop never exits } For example, caif_serial's handle_tx() enters an infinite loop when used with PORT_UNKNOWN serial ports, causing system hangs. Fix by making uart_write_room() also check xmit_buf and return 0 if it's NULL, consistent with uart_write(). Reproducer: https://gist.github.com/mrpre/d9a694cc0e19828ee3bc3b37983fde13 Signed-off-by: Jiayuan Chen <jiayuan.chen@shopee.com> Cc: stable <stable@kernel.org> Link: https://patch.msgid.link/20260204074327.226165-1-jiayuan.chen@linux.dev Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-03-25serial: 8250_dw: Ensure BUSY is deassertedIlpo Järvinen
commit a7b9ce39fbe4ae2919fe4f7ac16c293cb6632d30 upstream. DW UART cannot write to LCR, DLL, and DLH while BUSY is asserted. Existance of BUSY depends on uart_16550_compatible, if UART HW is configured with it those registers can always be written. There currently is dw8250_force_idle() which attempts to achieve non-BUSY state by disabling FIFO, however, the solution is unreliable when Rx keeps getting more and more characters. Create a sequence of operations that ensures UART cannot keep BUSY asserted indefinitely. The new sequence relies on enabling loopback mode temporarily to prevent incoming Rx characters keeping UART BUSY. Ensure no Tx in ongoing while the UART is switches into the loopback mode (requires exporting serial8250_fifo_wait_for_lsr_thre() and adding DMA Tx pause/resume functions). According to tests performed by Adriana Nicolae <adriana@arista.com>, simply disabling FIFO or clearing FIFOs only once does not always ensure BUSY is deasserted but up to two tries may be needed. This could be related to ongoing Rx of a character (a guess, not known for sure). Therefore, retry FIFO clearing a few times (retry limit 4 is arbitrary number but using, e.g., p->fifosize seems overly large). Tests performed by others did not exhibit similar challenge but it does not seem harmful to leave the FIFO clearing loop in place for all DW UARTs with BUSY functionality. Use the new dw8250_idle_enter/exit() to do divisor writes and LCR writes. In case of plain LCR writes, opportunistically try to update LCR first and only invoke dw8250_idle_enter() if the write did not succeed (it has been observed that in practice most LCR writes do succeed without complications). This issue was first reported by qianfan Zhao who put lots of debugging effort into understanding the solution space. Fixes: c49436b657d0 ("serial: 8250_dw: Improve unwritable LCR workaround") Fixes: 7d4008ebb1c9 ("tty: add a DesignWare 8250 driver") Cc: stable <stable@kernel.org> Reported-by: qianfan Zhao <qianfanguijin@163.com> Link: https://lore.kernel.org/linux-serial/289bb78a-7509-1c5c-2923-a04ed3b6487d@163.com/ Reported-by: Adriana Nicolae <adriana@arista.com> Link: https://lore.kernel.org/linux-serial/20250819182322.3451959-1-adriana@arista.com/ Reported-by: Bandal, Shankar <shankar.bandal@intel.com> Tested-by: Bandal, Shankar <shankar.bandal@intel.com> Tested-by: Murthy, Shanth <shanth.murthy@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://patch.msgid.link/20260203171049.4353-8-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-03-25serial: 8250: Add late synchronize_irq() to shutdown to handle DW UART BUSYIlpo Järvinen
commit e0a368ae79531ff92105a2692f10d83052055856 upstream. When DW UART is !uart_16550_compatible, it can indicate BUSY at any point (when under constant Rx pressure) unless a complex sequence of steps is performed. Any LCR write can run a foul with the condition that prevents writing LCR while the UART is BUSY, which triggers BUSY_DETECT interrupt that seems unmaskable using IER bits. Normal flow is that dw8250_handle_irq() handles BUSY_DETECT condition by reading USR register. This BUSY feature, however, breaks the assumptions made in serial8250_do_shutdown(), which runs synchronize_irq() after clearing IER and assumes no interrupts can occur after that point but then proceeds to update LCR, which on DW UART can trigger an interrupt. If serial8250_do_shutdown() releases the interrupt handler before the handler has run and processed the BUSY_DETECT condition by read the USR register, the IRQ is not deasserted resulting in interrupt storm that triggers "irq x: nobody cared" warning leading to disabling the IRQ. Add late synchronize_irq() into serial8250_do_shutdown() to ensure BUSY_DETECT from DW UART is handled before port's interrupt handler is released. Alternative would be to add DW UART specific shutdown function but it would mostly duplicate the generic code and the extra synchronize_irq() seems pretty harmless in serial8250_do_shutdown(). Fixes: 7d4008ebb1c9 ("tty: add a DesignWare 8250 driver") Cc: stable <stable@kernel.org> Reported-by: Bandal, Shankar <shankar.bandal@intel.com> Tested-by: Bandal, Shankar <shankar.bandal@intel.com> Tested-by: Murthy, Shanth <shanth.murthy@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://patch.msgid.link/20260203171049.4353-7-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-03-25serial: 8250_dw: Rework IIR_NO_INT handling to stop interrupt stormIlpo Järvinen
commit 73a4ed8f9efaaaf8207614ccc1c9d5ca1888f23a upstream. INTC10EE UART can end up into an interrupt storm where it reports IIR_NO_INT (0x1). If the storm happens during active UART operation, it is promptly stopped by IIR value change due to Rx or Tx events. However, when there is no activity, either due to idle serial line or due to specific circumstances such as during shutdown that writes IER=0, there is nothing to stop the storm. During shutdown the storm is particularly problematic because serial8250_do_shutdown() calls synchronize_irq() that will hang in waiting for the storm to finish which never happens. This problem can also result in triggering a warning: irq 45: nobody cared (try booting with the "irqpoll" option) [...snip...] handlers: serial8250_interrupt Disabling IRQ #45 Normal means to reset interrupt status by reading LSR, MSR, USR, or RX register do not result in the UART deasserting the IRQ. Add a quirk to INTC10EE UARTs to enable Tx interrupts if UART's Tx is currently empty and inactive. Rework IIR_NO_INT to keep track of the number of consecutive IIR_NO_INT, and on fourth one perform the quirk. Enabling Tx interrupts should change IIR value from IIR_NO_INT to IIR_THRI which has been observed to stop the storm. Fixes: e92fad024929 ("serial: 8250_dw: Add ACPI ID for Granite Rapids-D UART") Cc: stable <stable@kernel.org> Reported-by: Bandal, Shankar <shankar.bandal@intel.com> Tested-by: Bandal, Shankar <shankar.bandal@intel.com> Tested-by: Murthy, Shanth <shanth.murthy@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://patch.msgid.link/20260203171049.4353-6-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-03-25serial: 8250_dw: Rework dw8250_handle_irq() locking and IIR handlingIlpo Järvinen
commit 883c5a2bc934c165c4491d1ef7da0ac4e9765077 upstream. dw8250_handle_irq() takes port's lock multiple times with no good reason to release it in between and calls serial8250_handle_irq() that also takes port's lock. Take port's lock only once in dw8250_handle_irq() and use serial8250_handle_irq_locked() to avoid releasing port's lock in between. As IIR_NO_INT check in serial8250_handle_irq() was outside of port's lock, it has to be done already in dw8250_handle_irq(). DW UART can, in addition to IIR_NO_INT, report BUSY_DETECT (0x7) which collided with the IIR_NO_INT (0x1) check in serial8250_handle_irq() (because & is used instead of ==) meaning that no other work is done by serial8250_handle_irq() during an BUSY_DETECT interrupt. This allows reorganizing code in dw8250_handle_irq() to do both IIR_NO_INT and BUSY_DETECT handling right at the start simplifying the logic. Tested-by: Bandal, Shankar <shankar.bandal@intel.com> Tested-by: Murthy, Shanth <shanth.murthy@intel.com> Cc: stable <stable@kernel.org> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://patch.msgid.link/20260203171049.4353-5-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-03-25serial: 8250: Add serial8250_handle_irq_locked()Ilpo Järvinen
commit 8324a54f604da18f21070702a8ad82ab2062787b upstream. 8250_port exports serial8250_handle_irq() to HW specific 8250 drivers. It takes port's lock within but a HW specific 8250 driver may want to take port's lock itself, do something, and then call the generic handler in 8250_port but to do that, the caller has to release port's lock for no good reason. Introduce serial8250_handle_irq_locked() which a HW specific driver can call while already holding port's lock. As this is new export, put it straight into a namespace (where all 8250 exports should eventually be moved). Tested-by: Bandal, Shankar <shankar.bandal@intel.com> Tested-by: Murthy, Shanth <shanth.murthy@intel.com> Cc: stable <stable@kernel.org> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://patch.msgid.link/20260203171049.4353-4-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-03-25serial: 8250_dw: Avoid unnecessary LCR writesIlpo Järvinen
commit 8002d6d6d0d8a36a7d6ca523b17a51cb0fa7c3c3 upstream. When DW UART is configured with BUSY flag, LCR writes may not always succeed which can make any LCR write complex and very expensive. Performing write directly can trigger IRQ and the driver has to perform complex and distruptive sequence while retrying the write. Therefore, it's better to avoid doing LCR write that would not change the value of the LCR register. Add LCR write avoidance code into the 8250_dw driver's .serial_out() functions. Reported-by: Bandal, Shankar <shankar.bandal@intel.com> Tested-by: Bandal, Shankar <shankar.bandal@intel.com> Tested-by: Murthy, Shanth <shanth.murthy@intel.com> Cc: stable <stable@kernel.org> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://patch.msgid.link/20260203171049.4353-3-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>