linux-stable.git/drivers/tty, branch v4.17.2 Linux kernel stable tree tty: pl011: Avoid spuriously stuck-off interrupts 2018-06-16T07:18:22+00:00 Dave Martin Dave.Martin@arm.com 2018-05-10T17:08:23+00:00 f4764b7b1e989090a1ff54b6eecad72205d1570f commit 4a7e625ce50412a7711efa0f2ef0b96ce3826759 upstream. Commit 9b96fbacda34 ("serial: PL011: clear pending interrupts") clears the RX and receive timeout interrupts on pl011 startup, to avoid a screaming-interrupt scenario that can occur when the firmware or bootloader leaves these interrupts asserted. This has been noted as an issue when running Linux on qemu [1]. Unfortunately, the above fix seems to lead to potential misbehaviour if the RX FIFO interrupt is asserted _non_ spuriously on driver startup, if the RX FIFO is also already full to the trigger level. Clearing the RX FIFO interrupt does not change the FIFO fill level. In this scenario, because the interrupt is now clear and because the FIFO is already full to the trigger level, no new assertion of the RX FIFO interrupt can occur unless the FIFO is drained back below the trigger level. This never occurs because the pl011 driver is waiting for an RX FIFO interrupt to tell it that there is something to read, and does not read the FIFO at all until that interrupt occurs. Thus, simply clearing "spurious" interrupts on startup may be misguided, since there is no way to be sure that the interrupts are truly spurious, and things can go wrong if they are not. This patch instead clears the interrupt condition by draining the RX FIFO during UART startup, after clearing any potentially spurious interrupt. This should ensure that an interrupt will definitely be asserted if the RX FIFO subsequently becomes sufficiently full. The drain is done at the point of enabling interrupts only. This means that it will occur any time the UART is newly opened through the tty layer. It will not apply to polled-mode use of the UART by kgdboc: since that scenario cannot use interrupts by design, this should not matter. kgdboc will interact badly with "normal" use of the UART in any case: this patch makes no attempt to paper over such issues. This patch does not attempt to address the case where the RX FIFO fills faster than it can be drained: that is a pathological hardware design problem that is beyond the scope of the driver to work around. As a failsafe, the number of poll iterations for draining the FIFO is limited to twice the FIFO size. This will ensure that the kernel at least boots even if it is impossible to drain the FIFO for some reason. [1] [Qemu-devel] [Qemu-arm] [PATCH] pl011: do not put into fifo before enabled the interruption https://lists.gnu.org/archive/html/qemu-devel/2018-01/msg06446.html Reported-by: Wei Xu <xuwei5@hisilicon.com> Cc: Russell King <linux@armlinux.org.uk> Cc: Linus Walleij <linus.walleij@linaro.org> Cc: Peter Maydell <peter.maydell@linaro.org> Fixes: 9b96fbacda34 ("serial: PL011: clear pending interrupts") Signed-off-by: Dave Martin <Dave.Martin@arm.com> Cc: stable <stable@vger.kernel.org> Tested-by: Wei Xu <xuwei5@hisilicon.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 4a7e625ce50412a7711efa0f2ef0b96ce3826759 upstream.

Commit 9b96fbacda34 ("serial: PL011: clear pending interrupts")
clears the RX and receive timeout interrupts on pl011 startup, to
avoid a screaming-interrupt scenario that can occur when the
firmware or bootloader leaves these interrupts asserted.

This has been noted as an issue when running Linux on qemu [1].

Unfortunately, the above fix seems to lead to potential
misbehaviour if the RX FIFO interrupt is asserted _non_ spuriously
on driver startup, if the RX FIFO is also already full to the
trigger level.

Clearing the RX FIFO interrupt does not change the FIFO fill level.
In this scenario, because the interrupt is now clear and because
the FIFO is already full to the trigger level, no new assertion of
the RX FIFO interrupt can occur unless the FIFO is drained back
below the trigger level.  This never occurs because the pl011
driver is waiting for an RX FIFO interrupt to tell it that there is
something to read, and does not read the FIFO at all until that
interrupt occurs.

Thus, simply clearing "spurious" interrupts on startup may be
misguided, since there is no way to be sure that the interrupts are
truly spurious, and things can go wrong if they are not.

This patch instead clears the interrupt condition by draining the
RX FIFO during UART startup, after clearing any potentially
spurious interrupt.  This should ensure that an interrupt will
definitely be asserted if the RX FIFO subsequently becomes
sufficiently full.

The drain is done at the point of enabling interrupts only.  This
means that it will occur any time the UART is newly opened through
the tty layer.  It will not apply to polled-mode use of the UART by
kgdboc: since that scenario cannot use interrupts by design, this
should not matter.  kgdboc will interact badly with "normal" use of
the UART in any case: this patch makes no attempt to paper over
such issues.

This patch does not attempt to address the case where the RX FIFO
fills faster than it can be drained: that is a pathological
hardware design problem that is beyond the scope of the driver to
work around.  As a failsafe, the number of poll iterations for
draining the FIFO is limited to twice the FIFO size.  This will
ensure that the kernel at least boots even if it is impossible to
drain the FIFO for some reason.

[1] [Qemu-devel] [Qemu-arm] [PATCH] pl011: do not put into fifo
before enabled the interruption
https://lists.gnu.org/archive/html/qemu-devel/2018-01/msg06446.html

Reported-by: Wei Xu <xuwei5@hisilicon.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Peter Maydell <peter.maydell@linaro.org>
Fixes: 9b96fbacda34 ("serial: PL011: clear pending interrupts")
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Cc: stable <stable@vger.kernel.org>
Tested-by: Wei Xu <xuwei5@hisilicon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: 8250: omap: Fix idling of clocks for unused uarts 2018-06-16T07:18:22+00:00 Tony Lindgren tony@atomide.com 2018-05-04T17:44:09+00:00 592141182e63a1bc901024404581d3d00d1f09bb commit 13dc04d0e5fdc25c8f713ad23fdce51cf2bf96ba upstream. I noticed that unused UARTs won't necessarily idle properly always unless at least one byte tx transfer is done first. After some debugging I narrowed down the problem to the scr register dma configuration bits that need to be set before softreset for the clocks to idle. Unless we do this, the module clkctrl idlest bits may be set to 1 instead of 3 meaning the clock will never idle and is blocking deeper idle states for the whole domain. This might be related to the configuration done by the bootloader or kexec booting where certain configurations cause the 8250 or the clkctrl clock to jam in a way where setting of the scr bits and reset is needed to clear it. I've tried diffing the 8250 registers for the various modes, but did not see anything specific. So far I've only seen this on omap4 but I'm suspecting this might also happen on the other clkctrl using SoCs considering they already have a quirk enabled for UART_ERRATA_CLOCK_DISABLE. Let's fix the issue by configuring scr before reset for basic dma even if we don't use it. The scr register will be reset when we do softreset few lines after, and we restore scr on resume. We should do this for all the SoCs with UART_ERRATA_CLOCK_DISABLE quirk flag set since the ones with UART_ERRATA_CLOCK_DISABLE are all based using clkctrl similar to omap4. Looks like both OMAP_UART_SCR_DMAMODE_1 | OMAP_UART_SCR_DMAMODE_CTL bits are needed for the clkctrl to idle after a softreset. And we need to add omap4 to also use the UART_ERRATA_CLOCK_DISABLE for the related workaround to be enabled. This same compatible value will also be used for omap5. Fixes: cdb929e4452a ("serial: 8250_omap: workaround errata around idling UART after using DMA") Cc: Keerthy <j-keerthy@ti.com> Cc: Matthijs van Duin <matthijsvanduin@gmail.com> Cc: Sekhar Nori <nsekhar@ti.com> Cc: Tero Kristo <t-kristo@ti.com> Signed-off-by: Tony Lindgren <tony@atomide.com> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 13dc04d0e5fdc25c8f713ad23fdce51cf2bf96ba upstream.

I noticed that unused UARTs won't necessarily idle properly always
unless at least one byte tx transfer is done first.

After some debugging I narrowed down the problem to the scr register
dma configuration bits that need to be set before softreset for the
clocks to idle. Unless we do this, the module clkctrl idlest bits
may be set to 1 instead of 3 meaning the clock will never idle and
is blocking deeper idle states for the whole domain.

This might be related to the configuration done by the bootloader
or kexec booting where certain configurations cause the 8250 or
the clkctrl clock to jam in a way where setting of the scr bits
and reset is needed to clear it. I've tried diffing the 8250
registers for the various modes, but did not see anything specific.
So far I've only seen this on omap4 but I'm suspecting this might
also happen on the other clkctrl using SoCs considering they
already have a quirk enabled for UART_ERRATA_CLOCK_DISABLE.

Let's fix the issue by configuring scr before reset for basic dma
even if we don't use it. The scr register will be reset when we do
softreset few lines after, and we restore scr on resume. We should
do this for all the SoCs with UART_ERRATA_CLOCK_DISABLE quirk flag
set since the ones with UART_ERRATA_CLOCK_DISABLE are all based
using clkctrl similar to omap4.

Looks like both OMAP_UART_SCR_DMAMODE_1 | OMAP_UART_SCR_DMAMODE_CTL
bits are needed for the clkctrl to idle after a softreset.

And we need to add omap4 to also use the UART_ERRATA_CLOCK_DISABLE
for the related workaround to be enabled. This same compatible
value will also be used for omap5.

Fixes: cdb929e4452a ("serial: 8250_omap: workaround errata around idling UART after using DMA")
Cc: Keerthy <j-keerthy@ti.com>
Cc: Matthijs van Duin <matthijsvanduin@gmail.com>
Cc: Sekhar Nori <nsekhar@ti.com>
Cc: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: samsung: fix maxburst parameter for DMA transactions 2018-06-16T07:18:22+00:00 Marek Szyprowski m.szyprowski@samsung.com 2018-05-10T06:41:13+00:00 c8f1940e3a7aae8499cff94eab1b50f69038d66f commit aa2f80e752c75e593b3820f42c416ed9458fa73e upstream. The best granularity of residue that DMA engine can report is in the BURST units, so the serial driver must use MAXBURST = 1 and DMA_SLAVE_BUSWIDTH_1_BYTE if it relies on exact number of bytes transferred by DMA engine. Fixes: 62c37eedb74c ("serial: samsung: add dma reqest/release functions") Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Acked-by: Krzysztof Kozlowski <krzk@kernel.org> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit aa2f80e752c75e593b3820f42c416ed9458fa73e upstream.

The best granularity of residue that DMA engine can report is in the BURST
units, so the serial driver must use MAXBURST = 1 and DMA_SLAVE_BUSWIDTH_1_BYTE
if it relies on exact number of bytes transferred by DMA engine.

Fixes: 62c37eedb74c ("serial: samsung: add dma reqest/release functions")
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty/serial: atmel: use port->name as name in request_irq() 2018-06-16T07:18:22+00:00 Sebastian Andrzej Siewior bigeasy@linutronix.de 2018-05-07T17:11:30+00:00 ab7a1943955a82b01982fe182f3f8df1372022fa commit 9594b5be7ec110ed11acec58fa94f3f293668c85 upstream. I was puzzled while looking at /proc/interrupts and random things showed up between reboots. This occurred more often but I realised it later. The "correct" output should be: |38: 11861 atmel-aic5 2 Level ttyS0 but I saw sometimes |38: 6426 atmel-aic5 2 Level tty1 and accounted it wrongly as correct. This is use after free and the former example randomly got the "old" pointer which pointed to the same content. With SLAB_FREELIST_RANDOM and HARDENED I even got |38: 7067 atmel-aic5 2 Level E=Started User Manager for UID 0 or other nonsense. As it turns out the tty, pointer that is accessed in atmel_startup(), is freed() before atmel_shutdown(). It seems to happen quite often that the tty for ttyS0 is allocated and freed while ->shutdown is not invoked. I don't do anything special - just a systemd boot :) Use dev_name(&pdev->dev) as the IRQ name for request_irq(). This exists as long as the driver is loaded so no use-after-free here. Cc: stable@vger.kernel.org Fixes: 761ed4a94582 ("tty: serial_core: convert uart_close to use tty_port_close") Acked-by: Richard Genoud <richard.genoud@gmail.com> Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 9594b5be7ec110ed11acec58fa94f3f293668c85 upstream.

I was puzzled while looking at /proc/interrupts and random things showed
up between reboots. This occurred more often but I realised it later. The
"correct" output should be:
|38:      11861  atmel-aic5   2 Level     ttyS0

but I saw sometimes
|38:       6426  atmel-aic5   2 Level     tty1

and accounted it wrongly as correct. This is use after free and the
former example randomly got the "old" pointer which pointed to the same
content. With SLAB_FREELIST_RANDOM and HARDENED I even got
|38:       7067  atmel-aic5   2 Level     E=Started User Manager for UID 0

or other nonsense.
As it turns out the tty, pointer that is accessed in atmel_startup(), is
freed() before atmel_shutdown(). It seems to happen quite often that the
tty for ttyS0 is allocated and freed while ->shutdown is not invoked. I
don't do anything special - just a systemd boot :)

Use dev_name(&pdev->dev) as the IRQ name for request_irq(). This exists
as long as the driver is loaded so no use-after-free here.

Cc: stable@vger.kernel.org
Fixes: 761ed4a94582 ("tty: serial_core: convert uart_close to use tty_port_close")
Acked-by: Richard Genoud <richard.genoud@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: sh-sci: Stop using printk format %pCr 2018-06-16T07:18:21+00:00 Geert Uytterhoeven geert+renesas@glider.be 2018-06-01T09:28:21+00:00 6f7e40b8797e44923552663369dd749fc7bea6ac commit d63c16f8e1ab761775275adcf54f4bef7c330295 upstream. Printk format "%pCr" will be removed soon, as clk_get_rate() must not be called in atomic context. Replace it by open-coding the operation. This is safe here, as the code runs in task context. Link: http://lkml.kernel.org/r/1527845302-12159-4-git-send-email-geert+renesas@glider.be To: Jia-Ju Bai <baijiaju1990@gmail.com> To: Jonathan Corbet <corbet@lwn.net> To: Michael Turquette <mturquette@baylibre.com> To: Stephen Boyd <sboyd@kernel.org> To: Zhang Rui <rui.zhang@intel.com> To: Eduardo Valentin <edubezval@gmail.com> To: Eric Anholt <eric@anholt.net> To: Stefan Wahren <stefan.wahren@i2se.com> To: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: linux-doc@vger.kernel.org Cc: linux-clk@vger.kernel.org Cc: linux-pm@vger.kernel.org Cc: linux-serial@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-renesas-soc@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: Geert Uytterhoeven <geert+renesas@glider.be> Cc: stable@vger.kernel.org # 4.5+ Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit d63c16f8e1ab761775275adcf54f4bef7c330295 upstream.

Printk format "%pCr" will be removed soon, as clk_get_rate() must not be
called in atomic context.

Replace it by open-coding the operation.  This is safe here, as the code
runs in task context.

Link: http://lkml.kernel.org/r/1527845302-12159-4-git-send-email-geert+renesas@glider.be
To: Jia-Ju Bai <baijiaju1990@gmail.com>
To: Jonathan Corbet <corbet@lwn.net>
To: Michael Turquette <mturquette@baylibre.com>
To: Stephen Boyd <sboyd@kernel.org>
To: Zhang Rui <rui.zhang@intel.com>
To: Eduardo Valentin <edubezval@gmail.com>
To: Eric Anholt <eric@anholt.net>
To: Stefan Wahren <stefan.wahren@i2se.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-doc@vger.kernel.org
Cc: linux-clk@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Cc: linux-serial@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-renesas-soc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: stable@vger.kernel.org # 4.5+
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: Use __GFP_NOFAIL for tty_ldisc_get() 2018-04-25T13:03:44+00:00 Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp 2018-04-25T11:12:31+00:00 bcdd0ca8cb8730573afebcaae4138f8f4c8eaa20 syzbot is reporting crashes triggered by memory allocation fault injection at tty_ldisc_get() [1]. As an attempt to handle OOM in a graceful way, we have tried commit 5362544bebe85071 ("tty: don't panic on OOM in tty_set_ldisc()"). But we reverted that attempt by commit a8983d01f9b7d600 ("Revert "tty: don't panic on OOM in tty_set_ldisc()"") due to reproducible crash. We should spend resource for finding and fixing race condition bugs rather than complicate error paths for 2 * sizeof(void *) bytes allocation failure. [1] https://syzkaller.appspot.com/bug?id=489d33fa386453859ead58ff5171d43772b13aa3 Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reported-by: syzbot <syzbot+40b7287c2dc987c48c81@syzkaller.appspotmail.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Vegard Nossum <vegard.nossum@gmail.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
syzbot is reporting crashes triggered by memory allocation fault injection
at tty_ldisc_get() [1]. As an attempt to handle OOM in a graceful way, we
have tried commit 5362544bebe85071 ("tty: don't panic on OOM in
tty_set_ldisc()"). But we reverted that attempt by commit a8983d01f9b7d600
("Revert "tty: don't panic on OOM in tty_set_ldisc()"") due to reproducible
crash. We should spend resource for finding and fixing race condition bugs
rather than complicate error paths for 2 * sizeof(void *) bytes allocation
failure.

[1] https://syzkaller.appspot.com/bug?id=489d33fa386453859ead58ff5171d43772b13aa3

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: syzbot <syzbot+40b7287c2dc987c48c81@syzkaller.appspotmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vegard Nossum <vegard.nossum@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: serial: xuartps: Setup early console when uartclk is also passed 2018-04-23T09:12:22+00:00 Michal Simek michal.simek@xilinx.com 2018-04-23T08:55:21+00:00 66dd99c2033684169f04068f66c7f83f7da229b8 Baudrate calculation depends on requested baudrate and uart clock. This patch is checking that uartclk is also passed. The same logic is used 8250_early.c/init_port function. Signed-off-by: Michal Simek <michal.simek@xilinx.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Baudrate calculation depends on requested baudrate and uart clock.
This patch is checking that uartclk is also passed.

The same logic is used 8250_early.c/init_port function.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: Don't call panic() at tty_ldisc_init() 2018-04-23T09:05:52+00:00 Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp 2018-04-05T10:40:16+00:00 903f9db10f18f735e62ba447147b6c434b6af003 syzbot is reporting kernel panic [1] triggered by memory allocation failure at tty_ldisc_get() from tty_ldisc_init(). But since both tty_ldisc_get() and caller of tty_ldisc_init() can cleanly handle errors, tty_ldisc_init() does not need to call panic() when tty_ldisc_get() failed. [1] https://syzkaller.appspot.com/bug?id=883431818e036ae6a9981156a64b821110f39187 Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reported-by: syzbot <syzkaller@googlegroups.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jiri Slaby <jslaby@suse.com> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
syzbot is reporting kernel panic [1] triggered by memory allocation failure
at tty_ldisc_get() from tty_ldisc_init(). But since both tty_ldisc_get()
and caller of tty_ldisc_init() can cleanly handle errors, tty_ldisc_init()
does not need to call panic() when tty_ldisc_get() failed.

[1] https://syzkaller.appspot.com/bug?id=883431818e036ae6a9981156a64b821110f39187

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: Avoid possible error pointer dereference at tty_ldisc_restore(). 2018-04-23T09:05:52+00:00 Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp 2018-04-16T11:06:34+00:00 598c2d41ff44889dd8eced4f117403e472158d85 syzbot is reporting crashes [1] triggered by memory allocation failure at tty_ldisc_get() from tty_ldisc_restore(). While syzbot stops at WARN_ON() due to panic_on_warn == true, panic_on_warn == false will after all trigger an OOPS by dereferencing old->ops->num if IS_ERR(old) == true. We can simplify tty_ldisc_restore() as three calls (old->ops->num, N_TTY, N_NULL) to tty_ldisc_failto() in addition to avoiding possible error pointer dereference. If someone reports kernel panic triggered by forcing all memory allocations for tty_ldisc_restore() to fail, we can consider adding __GFP_NOFAIL for tty_ldisc_restore() case. [1] https://syzkaller.appspot.com/bug?id=6ac359c61e71d22e06db7f8f88243feb11d927e7 Reported-by: syzbot+40b7287c2dc987c48c81@syzkaller.appspotmail.com Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jiri Slaby <jslaby@suse.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Alan Cox <alan@llwyncelyn.cymru> Cc: Christoph Hellwig <hch@lst.de> Cc: Michal Hocko <mhocko@suse.com> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
syzbot is reporting crashes [1] triggered by memory allocation failure at
tty_ldisc_get() from tty_ldisc_restore(). While syzbot stops at WARN_ON()
due to panic_on_warn == true, panic_on_warn == false will after all trigger
an OOPS by dereferencing old->ops->num if IS_ERR(old) == true.

We can simplify tty_ldisc_restore() as three calls (old->ops->num, N_TTY,
N_NULL) to tty_ldisc_failto() in addition to avoiding possible error
pointer dereference.

If someone reports kernel panic triggered by forcing all memory allocations
for tty_ldisc_restore() to fail, we can consider adding __GFP_NOFAIL for
tty_ldisc_restore() case.

[1] https://syzkaller.appspot.com/bug?id=6ac359c61e71d22e06db7f8f88243feb11d927e7

Reported-by: syzbot+40b7287c2dc987c48c81@syzkaller.appspotmail.com
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Alan Cox <alan@llwyncelyn.cymru>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: serial: qcom_geni_serial: Use signed variable to get IRQ 2018-04-23T08:22:30+00:00 Karthikeyan Ramasubramanian kramasub@codeaurora.org 2018-04-07T00:49:00+00:00 066cd1c4e4b9b43116f2bf0f4a84ac7235e7abec The platform_get_irq can return error. Assigning the return value to an unsigned variable and checking it for negative value will always return false. Use an intermediate signed variable to get IRQ information, check for any error and then assign it to 'irq' variable inside uart_port structure. Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org> Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by: Stephen Boyd <swboyd@chromium.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
The platform_get_irq can return error. Assigning the return value to an
unsigned variable and checking it for negative value will always return
false.

Use an intermediate signed variable to get IRQ information, check for any
error and then assign it to 'irq' variable inside uart_port structure.

Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>