linux-stable.git/drivers/usb, branch v7.2.3 Linux kernel stable tree usb: usbfs: fix use-after-free of usb_device in usbdev_release() 2026-09-02T12:33:21+00:00 Miguel Peñaranda mig.penaranda07@gmail.com 2026-08-10T12:12:09+00:00 47a7f98fbb5006d46d15a3a210ffdc61448a4f19 commit 0dd68b5d01d022fc9c5e71c82a82b0a94d3d0671 upstream. usbdev_release() drops its reference to the struct usb_device before draining the list of completed async URBs, but that drain path reads back through the same object: free_async() calls dec_usb_memory_use_count() for any URB whose buffer came from the usbfs mmap() region, and its first statement is bus_to_hcd(ps->dev->bus). After a disconnect the usbfs reference can be the last one, in which case usb_put_dev() frees the device and the subsequent loop reads offset 80 of freed memory and uses the result as a struct usb_hcd *, which hcd_buffer_free_pages() then dereferences. This is reachable by an unprivileged process that has read/write access to a /dev/bus/usb node: mmap() the fd, submit one URB with a buffer inside the mapping, wait for the device to be unplugged, then munmap() and close(). It reproduces on every attempt rather than being a race, because a live MAP_SHARED vma holds a reference on the struct file, so usbdev_release() cannot run until the last vma is gone and the freeing branch of dec_usb_memory_use_count() is always taken. BUG: KASAN: slab-use-after-free in dec_usb_memory_use_count+0x3ae/0x410 Read of size 8 at addr ffff8880122ee050 by task poc/769 CPU: 1 UID: 1000 PID: 769 Comm: poc Tainted: G B 6.12.94 #3 Call Trace: dec_usb_memory_use_count+0x3ae/0x410 free_async+0x2aa/0x4f0 usbdev_release+0x375/0x460 __fput+0x3ea/0xb50 __x64_sys_close+0x86/0x100 Allocated by task 11: usb_alloc_dev+0x55/0xd90 hub_event+0x2524/0x43d0 Freed by task 769: kfree+0x121/0x360 device_release+0xd2/0x280 usb_put_dev+0x23/0x30 usbdev_release+0x2d8/0x460 Release the device reference after the drain loop instead. Nothing between the two points requires it to have been dropped. Fixes: f7d34b445abc ("USB: Add support for usbfs zerocopy.") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-5 Signed-off-by: Miguel Peñaranda <mig.penaranda07@gmail.com> Reviewed-by: Alan Stern <stern@rowland.harvard.edu> Link: https://patch.msgid.link/20260810121209.795089-1-mig.penaranda07@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 0dd68b5d01d022fc9c5e71c82a82b0a94d3d0671 upstream.

usbdev_release() drops its reference to the struct usb_device before
draining the list of completed async URBs, but that drain path reads back
through the same object: free_async() calls dec_usb_memory_use_count()
for any URB whose buffer came from the usbfs mmap() region, and its first
statement is bus_to_hcd(ps->dev->bus).

After a disconnect the usbfs reference can be the last one, in which case
usb_put_dev() frees the device and the subsequent loop reads offset 80 of
freed memory and uses the result as a struct usb_hcd *, which
hcd_buffer_free_pages() then dereferences.

This is reachable by an unprivileged process that has read/write access to
a /dev/bus/usb node: mmap() the fd, submit one URB with a buffer inside the
mapping, wait for the device to be unplugged, then munmap() and close().
It reproduces on every attempt rather than being a race, because a live
MAP_SHARED vma holds a reference on the struct file, so usbdev_release()
cannot run until the last vma is gone and the freeing branch of
dec_usb_memory_use_count() is always taken.

  BUG: KASAN: slab-use-after-free in dec_usb_memory_use_count+0x3ae/0x410
  Read of size 8 at addr ffff8880122ee050 by task poc/769
  CPU: 1 UID: 1000 PID: 769 Comm: poc Tainted: G    B    6.12.94 #3

  Call Trace:
   dec_usb_memory_use_count+0x3ae/0x410
   free_async+0x2aa/0x4f0
   usbdev_release+0x375/0x460
   __fput+0x3ea/0xb50
   __x64_sys_close+0x86/0x100

  Allocated by task 11:
   usb_alloc_dev+0x55/0xd90
   hub_event+0x2524/0x43d0

  Freed by task 769:
   kfree+0x121/0x360
   device_release+0xd2/0x280
   usb_put_dev+0x23/0x30
   usbdev_release+0x2d8/0x460

Release the device reference after the drain loop instead. Nothing between
the two points requires it to have been dropped.

Fixes: f7d34b445abc ("USB: Add support for usbfs zerocopy.")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-5
Signed-off-by: Miguel Peñaranda <mig.penaranda07@gmail.com>
Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://patch.msgid.link/20260810121209.795089-1-mig.penaranda07@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
USB: c67x00: fix use-after-free in c67x00_add_iso_urb() 2026-09-02T12:33:21+00:00 Shuangpeng Bai shuangpeng.kernel@gmail.com 2026-08-06T01:35:02+00:00 f24dcc61bd0ecf7639fac5bf700450b398d793a7 commit b1e24de475bf2d66fffc9103f3444b783527d55a upstream. When TD creation fails for the last packet of an isochronous URB, c67x00_add_iso_urb() gives the URB back before updating the endpoint scheduling state. c67x00_giveback_urb() frees the URB private data, and the completion callback may release the final URB reference. The following accesses to urbp->ep_data, urb->interval, and urbp->cnt can therefore use freed memory. Update next_frame and cnt before giving back the failed final packet, making the giveback the last operation that uses the URB and its private data. Fixes: e9b29ffc519b ("USB: add Cypress c67x00 OTG controller HCD driver") Cc: stable@vger.kernel.org Signed-off-by: Shuangpeng Bai <shuangpeng.kernel@gmail.com> Link: https://patch.msgid.link/20260806013502.322067-1-shuangpeng.kernel@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit b1e24de475bf2d66fffc9103f3444b783527d55a upstream.

When TD creation fails for the last packet of an isochronous URB,
c67x00_add_iso_urb() gives the URB back before updating the endpoint
scheduling state.

c67x00_giveback_urb() frees the URB private data, and the completion
callback may release the final URB reference. The following accesses to
urbp->ep_data, urb->interval, and urbp->cnt can therefore use freed
memory.

Update next_frame and cnt before giving back the failed final packet,
making the giveback the last operation that uses the URB and its private
data.

Fixes: e9b29ffc519b ("USB: add Cypress c67x00 OTG controller HCD driver")
Cc: stable@vger.kernel.org
Signed-off-by: Shuangpeng Bai <shuangpeng.kernel@gmail.com>
Link: https://patch.msgid.link/20260806013502.322067-1-shuangpeng.kernel@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
USB: serial: spcp8x5: drop broken carrier detect support 2026-09-02T12:33:21+00:00 Johan Hovold johan@kernel.org 2026-08-06T13:52:48+00:00 3720311fa519f273dc5c05086d956f3db62cac7b commit d37186bd95a07e334447f47274a38a311dad2172 upstream. The driver does not support modem status notifications and instead used to fetch the modem status once at open() and subsequently operate on and report stale state. As part of fixing this, a call to fetch the status was added to carrier_raised(), which does not work as that callback must not sleep (e.g. unlike tiocmget()). Drop the broken carrier detect support. Fixes: e1ed212d8593 ("USB: spcp8x5: add proper modem-status support") Cc: stable@vger.kernel.org # 3.10 Reported-by: syzbot+3b514b87202742f22c44@syzkaller.appspotmail.com Link: https://lore.kernel.org/all/6a73cea2.01d0871a.3a0d52.000d.GAE@google.com Signed-off-by: Johan Hovold <johan@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit d37186bd95a07e334447f47274a38a311dad2172 upstream.

The driver does not support modem status notifications and instead used
to fetch the modem status once at open() and subsequently operate on and
report stale state.

As part of fixing this, a call to fetch the status was added to
carrier_raised(), which does not work as that callback must not sleep
(e.g. unlike tiocmget()).

Drop the broken carrier detect support.

Fixes: e1ed212d8593 ("USB: spcp8x5: add proper modem-status support")
Cc: stable@vger.kernel.org	# 3.10
Reported-by: syzbot+3b514b87202742f22c44@syzkaller.appspotmail.com
Link: https://lore.kernel.org/all/6a73cea2.01d0871a.3a0d52.000d.GAE@google.com
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
USB: serial: option: fix slab OOB read in interrupt URB callback 2026-09-02T12:33:21+00:00 Jiale Yao yaojiale02@163.com 2026-07-25T16:27:51+00:00 d762aef4eba354066be21a5d88eb2066e282f4c9 commit 885d802f544ca7bfa8f3984d94233cce715bb6b3 upstream. The interrupt URB buffer is allocated in setup_port_interrupt_in() based on the endpoint's wMaxPacketSize: buffer_size = usb_endpoint_maxp(epd); port->interrupt_in_buffer = kmalloc(buffer_size, GFP_KERNEL); When a USB device declares wMaxPacketSize = 8 on its interrupt IN endpoint, the buffer is allocated from kmalloc-8 cache (exactly 8 bytes). If the device sends a short packet (actual_length < wMaxPacketSize), the URB completes with status == 0 and the callback proceeds to read: data[sizeof(struct usb_ctrlrequest)] which evaluates to data[8], accessing 1 byte beyond the allocated 8-byte buffer. This results in a slab out-of-bounds read. Fix this by adding the missing bounds check: first verify that the actual length is large enough to contain the struct usb_ctrlrequest header before accessing req_pkt->bRequestType and req_pkt->bRequest, and then verify that there is an additional byte for the modem signal state before reading data[sizeof(struct usb_ctrlrequest)] inside the conditional. Use sizeof(*req_pkt) instead of sizeof(struct usb_ctrlrequest) for consistency. Assisted-by: Claude:deepseek-v4-pro Signed-off-by: Jiale Yao <yaojiale02@163.com> Fixes: 58cfe9113e48 ("[PATCH] USB: add Option Card driver") Cc: stable@vger.kernel.org # v2.6.12 [ johan: use dev_err(); split signals declaration and initialisation ] Signed-off-by: Johan Hovold <johan@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 885d802f544ca7bfa8f3984d94233cce715bb6b3 upstream.

The interrupt URB buffer is allocated in setup_port_interrupt_in() based
on the endpoint's wMaxPacketSize:

    buffer_size = usb_endpoint_maxp(epd);
    port->interrupt_in_buffer = kmalloc(buffer_size, GFP_KERNEL);

When a USB device declares wMaxPacketSize = 8 on its interrupt IN
endpoint, the buffer is allocated from kmalloc-8 cache (exactly
8 bytes).

If the device sends a short packet (actual_length < wMaxPacketSize),
the URB completes with status == 0 and the callback proceeds to read:

    data[sizeof(struct usb_ctrlrequest)]

which evaluates to data[8], accessing 1 byte beyond the allocated 8-byte
buffer. This results in a slab out-of-bounds read.

Fix this by adding the missing bounds check: first verify that the
actual length is large enough to contain the struct usb_ctrlrequest
header before accessing req_pkt->bRequestType and req_pkt->bRequest,
and then verify that there is an additional byte for the modem signal
state before reading data[sizeof(struct usb_ctrlrequest)] inside the
conditional.  Use sizeof(*req_pkt) instead of sizeof(struct
usb_ctrlrequest) for consistency.

Assisted-by: Claude:deepseek-v4-pro
Signed-off-by: Jiale Yao <yaojiale02@163.com>
Fixes: 58cfe9113e48 ("[PATCH] USB: add Option Card driver")
Cc: stable@vger.kernel.org	# v2.6.12
[ johan: use dev_err(); split signals declaration and initialisation ]
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
usb: core: Strengthen error handling in hub_hub_status() 2026-09-02T12:33:21+00:00 Griffin Kroah-Hartman griffin@kroah.com 2026-07-22T08:17:39+00:00 b471594da637dcd5ee5e93d12a28d5c3716704cf commit a29496745aa335d97f617385809583241e118610 upstream. Add additional error handling after the call to get_hub_status() in hub_hub_status(). get_hub_status() uses usb_control_msg() which does not verify that the message is the correct length, substituting it for usb_control_msg_recv() would also solve this issue but increase memory allocations. Instead, error handling is copied from the method used in hub_ext_port_status(), which shares the same flow of logic as hub_hub_status(). Assisted-by: gkh_clanker_t1000 Signed-off-by: Griffin Kroah-Hartman <griffin@kroah.com> Link: https://patch.msgid.link/20260722-usb_core_patches_2-v3-1-87622252bfdd@kroah.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit a29496745aa335d97f617385809583241e118610 upstream.

Add additional error handling after the call to get_hub_status() in
hub_hub_status().

get_hub_status() uses usb_control_msg() which does not verify that the
message is the correct length, substituting it for
usb_control_msg_recv() would also solve this issue but increase memory
allocations.

Instead, error handling is copied from the method used in
hub_ext_port_status(), which shares the same flow of logic as
hub_hub_status().

Assisted-by: gkh_clanker_t1000
Signed-off-by: Griffin Kroah-Hartman <griffin@kroah.com>
Link: https://patch.msgid.link/20260722-usb_core_patches_2-v3-1-87622252bfdd@kroah.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
usb: core: Add lock to usb_wakeup_notification() 2026-09-02T12:33:21+00:00 Griffin Kroah-Hartman griffin@kroah.com 2026-07-13T15:43:53+00:00 7c48aa0c1e79116b8af4b988d16ee29b427d6491 commit e263e18a9e7b1ff3e7301f0801c6ff87c31adfb6 upstream. Add a spin lock to usb_wakeup notification to prevent a race condition with dereferencing freed memory. This could be hit by the xHCI driver as it calls this function from an IRQ and could race with the hub_disconnect() function, which properly grabs this lock to protect the state of the device. Assisted-by: gkh_clanker_t1000 Signed-off-by: Griffin Kroah-Hartman <griffin@kroah.com> Link: https://patch.msgid.link/20260713-usb_core_patches_1-v1-3-7721c2b33f53@kroah.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit e263e18a9e7b1ff3e7301f0801c6ff87c31adfb6 upstream.

Add a spin lock to usb_wakeup notification to prevent a race condition
with dereferencing freed memory. This could be hit by the xHCI driver as
it calls this function from an IRQ and could race with the
hub_disconnect() function, which properly grabs this lock to protect the
state of the device.

Assisted-by: gkh_clanker_t1000
Signed-off-by: Griffin Kroah-Hartman <griffin@kroah.com>
Link: https://patch.msgid.link/20260713-usb_core_patches_1-v1-3-7721c2b33f53@kroah.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
usb: gadget: f_tcm: keep port count until LUN teardown completes 2026-09-02T12:33:18+00:00 Shuangpeng Bai shuangpeng.kernel@gmail.com 2026-08-07T06:07:33+00:00 eaa96a8458f54d6cf0954242ab8b1df2a6fccafa commit c39d0916da47d94909391876c9e5bd429ea7b1b9 upstream. tcm_usbg_drop_nexus() permits session removal once tpg_port_count reaches zero. However, usbg_port_unlink() currently decrements that count from the fabric_pre_unlink() callback, before core_dev_del_lun() waits for active se_lun references to drain. If removal of the last LUN races a nexus removal, the latter can observe a zero port count and call target_remove_session(). This frees sess_cmd_map while an in-flight struct usbg_cmd, including its work item, can still be accessed. Overlapping the last-LUN unlink with nexus removal reproduces this lifetime violation as a DEBUG_OBJECTS "free active" warning for usbg_cmd_work, followed by a target-core BUG/Oops. The generic target-core unlink path has no callback after core_dev_del_lun() completes. Add an optional fabric_post_unlink() callback and use it for the f_tcm port count. The count now remains nonzero until core_dev_del_lun() has finished draining active LUN references, preventing nexus removal from freeing the session during command completion. Fixes: c52661d60f63 ("usb-gadget: Initial merge of target module for UASP + BOT") Cc: stable@vger.kernel.org Signed-off-by: Shuangpeng Bai <shuangpeng.kernel@gmail.com> Link: https://patch.msgid.link/20260807060733.3186624-1-shuangpeng.kernel@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit c39d0916da47d94909391876c9e5bd429ea7b1b9 upstream.

tcm_usbg_drop_nexus() permits session removal once tpg_port_count
reaches zero. However, usbg_port_unlink() currently decrements that
count from the fabric_pre_unlink() callback, before core_dev_del_lun()
waits for active se_lun references to drain.

If removal of the last LUN races a nexus removal, the latter can observe
a zero port count and call target_remove_session(). This frees
sess_cmd_map while an in-flight struct usbg_cmd, including its work item,
can still be accessed.

Overlapping the last-LUN unlink with nexus removal reproduces this
lifetime violation as a DEBUG_OBJECTS "free active" warning for
usbg_cmd_work, followed by a target-core BUG/Oops.

The generic target-core unlink path has no callback after
core_dev_del_lun() completes. Add an optional fabric_post_unlink()
callback and use it for the f_tcm port count. The count now remains
nonzero until core_dev_del_lun() has finished draining active LUN
references, preventing nexus removal from freeing the session during
command completion.

Fixes: c52661d60f63 ("usb-gadget: Initial merge of target module for UASP + BOT")
Cc: stable@vger.kernel.org
Signed-off-by: Shuangpeng Bai <shuangpeng.kernel@gmail.com>
Link: https://patch.msgid.link/20260807060733.3186624-1-shuangpeng.kernel@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
usb: usbtest: disable dynamic ID support 2026-09-02T12:33:18+00:00 Aleksandr Nogikh nogikh@google.com 2026-08-06T15:26:51+00:00 c6e90336ed7d75f949c20daa900e7a720504e8fd commit 00e2071f6d5621a5ddea311a5e6b143ae6e474af upstream. The usbtest driver relies on the driver_info field of struct usb_device_id to point to a valid struct usbtest_info descriptor. This structure contains essential test configurations, such as endpoint addresses and test modes, which are required during probe. When a user dynamically adds a new device ID via the sysfs new_id interface without specifying a reference device, the USB core initializes driver_info to 0 (NULL). When a matching device is subsequently probed, usbtest_probe() unconditionally casts driver_info to a struct usbtest_info pointer and dereferences it, leading to a NULL pointer dereference crash: Oops: general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] RIP: 0010:usbtest_probe+0x3b9/0x1280 drivers/usb/misc/usbtest.c:2822 Because usbtest strictly requires pre-defined usbtest_info descriptors to function, dynamic ID binding via sysfs is fundamentally unsupported for this driver. Fix this by setting .no_dynamic_id = 1 on usbtest_driver. This instructs the USB core to skip creating the new_id and remove_id sysfs interfaces for usbtest, preventing invalid dynamic ID entries from being created. Cc: stable@vger.kernel.org Reported-by: syzbot+7e1e5911f9eac50bedc7@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=7e1e5911f9eac50bedc7 Signed-off-by: Aleksandr Nogikh <nogikh@google.com> Tested-by: syzbot@syzkaller.appspotmail.com Link: https://patch.msgid.link/20260806152651.2370795-1-nogikh@google.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 00e2071f6d5621a5ddea311a5e6b143ae6e474af upstream.

The usbtest driver relies on the driver_info field of struct usb_device_id
to point to a valid struct usbtest_info descriptor. This structure contains
essential test configurations, such as endpoint addresses and test modes,
which are required during probe.

When a user dynamically adds a new device ID via the sysfs new_id
interface without specifying a reference device, the USB core initializes
driver_info to 0 (NULL). When a matching device is subsequently probed,
usbtest_probe() unconditionally casts driver_info to a struct usbtest_info
pointer and dereferences it, leading to a NULL pointer dereference crash:

  Oops: general protection fault, probably for non-canonical address
  0xdffffc0000000001: 0000 [#1] SMP KASAN NOPTI
  KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
  RIP: 0010:usbtest_probe+0x3b9/0x1280 drivers/usb/misc/usbtest.c:2822

Because usbtest strictly requires pre-defined usbtest_info descriptors
to function, dynamic ID binding via sysfs is fundamentally unsupported
for this driver.

Fix this by setting .no_dynamic_id = 1 on usbtest_driver. This instructs
the USB core to skip creating the new_id and remove_id sysfs interfaces
for usbtest, preventing invalid dynamic ID entries from being created.

Cc: stable@vger.kernel.org
Reported-by: syzbot+7e1e5911f9eac50bedc7@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=7e1e5911f9eac50bedc7
Signed-off-by: Aleksandr Nogikh <nogikh@google.com>
Tested-by: syzbot@syzkaller.appspotmail.com
Link: https://patch.msgid.link/20260806152651.2370795-1-nogikh@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
xhci: dbgtty: Fix unregister on tty_alloc_driver() failure 2026-09-02T12:33:17+00:00 Lucas De Marchi ldemarchi@nvidia.com 2026-08-06T14:21:04+00:00 57881714412d797d470af28e59de1760c76bf514 commit 25b8dfc13495a6c1cf4abacc8ef20196c7f20e5c upstream. Make sure to set dbc_tty_driver to NULL to match the check in dbc_tty_exit(). For that, make detached error handling path common to the other branch in the same function. Fixes: 4521f1613940 ("xhci: dbctty: split dbc tty driver registration and unregistration functions.") Cc: stable@vger.kernel.org # v5.10 Cc: Mathias Nyman <mathias.nyman@linux.intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Lucas De Marchi <ldemarchi@nvidia.com> Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com> Link: https://patch.msgid.link/20260806142113.2436238-9-mathias.nyman@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 25b8dfc13495a6c1cf4abacc8ef20196c7f20e5c upstream.

Make sure to set dbc_tty_driver to NULL to match the check in
dbc_tty_exit(). For that, make detached error handling path common to the
other branch in the same function.

Fixes: 4521f1613940 ("xhci: dbctty: split dbc tty driver registration and unregistration functions.")
Cc: stable@vger.kernel.org # v5.10
Cc: Mathias Nyman <mathias.nyman@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Lucas De Marchi <ldemarchi@nvidia.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://patch.msgid.link/20260806142113.2436238-9-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
xhci: dbgtty: Fix unregister on tty_register_driver() failure 2026-09-02T12:33:17+00:00 Lucas De Marchi ldemarchi@nvidia.com 2026-08-06T14:21:03+00:00 0e469b94fbba8eb03666da41dd1082b793c50c1a commit a916fa66a43e10f63198b6ce978badffc678821a upstream. If tty_register_driver() fails, it drops the reference, but fails to set the global dbc_tty_driver to NULL, causing the unregister to be called again when module exits. On module unload dbc_tty_exit() only gates its cleanup on the driver pointer being non-NULL, so it operates on the already-freed driver: module_init(xhci_hcd_init) xhci_hcd_init() xhci_dbc_init() [return value ignored] dbc_tty_init() tty_register_driver() fails tty_driver_kref_put() -> driver freed (dbc_tty_driver left dangling) ... module_exit(xhci_hcd_fini) xhci_hcd_fini() xhci_dbc_exit() dbc_tty_exit() if (dbc_tty_driver) -> true (dangling) tty_unregister_driver() -> use-after-free Fixes: 4521f1613940 ("xhci: dbctty: split dbc tty driver registration and unregistration functions.") Cc: stable@vger.kernel.org # v5.10 Cc: Mathias Nyman <mathias.nyman@linux.intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Lucas De Marchi <ldemarchi@nvidia.com> Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com> Link: https://patch.msgid.link/20260806142113.2436238-8-mathias.nyman@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit a916fa66a43e10f63198b6ce978badffc678821a upstream.

If tty_register_driver() fails, it drops the reference, but fails to set
the global dbc_tty_driver to NULL, causing the unregister to be called
again when module exits.

On module unload dbc_tty_exit() only gates its cleanup on the driver
pointer being non-NULL, so it operates on the already-freed driver:

    module_init(xhci_hcd_init)
      xhci_hcd_init()
        xhci_dbc_init()                       [return value ignored]
          dbc_tty_init()
            tty_register_driver() fails
              tty_driver_kref_put()           -> driver freed
              (dbc_tty_driver left dangling)
    ...
    module_exit(xhci_hcd_fini)
      xhci_hcd_fini()
        xhci_dbc_exit()
          dbc_tty_exit()
            if (dbc_tty_driver)               -> true (dangling)
              tty_unregister_driver()         -> use-after-free

Fixes: 4521f1613940 ("xhci: dbctty: split dbc tty driver registration and unregistration functions.")
Cc: stable@vger.kernel.org # v5.10
Cc: Mathias Nyman <mathias.nyman@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Lucas De Marchi <ldemarchi@nvidia.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://patch.msgid.link/20260806142113.2436238-8-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>