In the Linux kernel, the following vulnerability has been resolved:

usbip: vudc: Fix use after free bug in vudc_remove due to race condition

This patch follows up Zheng Wang's 2023 report of a use-after-free in
vudc_remove(). The original thread stalled on Shuah Khan's request for
runtime testing of the unplug/unbind path. This patch supplies that
testing and keeps Zheng's original fix shape.

In vudc_probe(), v_init_timer() binds udc->tr_timer.timer to v_timer().
usbip_sockfd_store() starts the timer via v_start_timer()/v_kick_timer().
vudc_remove() can then free the containing struct vudc while the timer is
still pending or executing.

KASAN confirms the race on an unpatched x86_64 QEMU guest with
CONFIG_KASAN=y, CONFIG_USBIP_VUDC=y, CONFIG_USB_ZERO=y, and a tight loop
that repeatedly writes a socket fd to usbip_sockfd, closes the socket
pair, and unbinds/rebinds usbip-vudc.0:

  BUG: KASAN: slab-use-after-free in __run_timer_base.part.0+0x8ba/0x8e0
  Write of size 8 at addr ffff888001b80740 by task trigger_and_unb/239
  Allocated by task 239:
    vudc_probe+0x4d/0xaa0
  Freed by task 239:
    kfree+0x18f/0x520
    device_release_driver_internal+0x388/0x540
    unbind_store+0xd9/0x100

This lands in the timer core rather than v_timer() itself because the
embedded timer_list is being walked after its containing struct vudc has
already been freed. The underlying lifetime bug is the same one Zheng
reported.

With v_stop_timer() called from vudc_remove() and the timer deleted
synchronously, the same harness completed 5000 bind/unbind iterations
with no KASAN report.

https://git.kernel.org/stable/c/1036ac6148995feaf486014d32bf26bf993c06a9

https://git.kernel.org/stable/c/207bf80362df3fce8ebc9723351dcb1bc6d9ed0f

https://git.kernel.org/stable/c/61704e5cf9cd7464b510eb606e7e2978b1160a64

https://git.kernel.org/stable/c/88d459e5b5a46da1ef9fd6f52d9439343edeec88

https://git.kernel.org/stable/c/a0638db2340ee053ab0450656a763fd111475e54

https://git.kernel.org/stable/c/d07ed707467ce05ea9c03412d0c5ee9d0fe386a6

https://git.kernel.org/stable/c/d96209626a29ea64666be98c30b30ac82e5f1be6

https://git.kernel.org/stable/c/dcc1c90b28b28b7c493547506297e78653f81952

[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","programFiles":["drivers/usb/usbip/vudc_dev.c","drivers/usb/usbip/vudc_transfer.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","versions":[{"version":"b6a0ca11186759ad7045d68a5447b1e89f658384","lessThan":"61704e5cf9cd7464b510eb606e7e2978b1160a64","versionType":"git","status":"affected"},{"version":"b6a0ca11186759ad7045d68a5447b1e89f658384","lessThan":"dcc1c90b28b28b7c493547506297e78653f81952","versionType":"git","status":"affected"},{"version":"b6a0ca11186759ad7045d68a5447b1e89f658384","lessThan":"1036ac6148995feaf486014d32bf26bf993c06a9","versionType":"git","status":"affected"},{"version":"b6a0ca11186759ad7045d68a5447b1e89f658384","lessThan":"a0638db2340ee053ab0450656a763fd111475e54","versionType":"git","status":"affected"},{"version":"b6a0ca11186759ad7045d68a5447b1e89f658384","lessThan":"d07ed707467ce05ea9c03412d0c5ee9d0fe386a6","versionType":"git","status":"affected"},{"version":"b6a0ca11186759ad7045d68a5447b1e89f658384","lessThan":"88d459e5b5a46da1ef9fd6f52d9439343edeec88","versionType":"git","status":"affected"},{"version":"b6a0ca11186759ad7045d68a5447b1e89f658384","lessThan":"207bf80362df3fce8ebc9723351dcb1bc6d9ed0f","versionType":"git","status":"affected"},{"version":"b6a0ca11186759ad7045d68a5447b1e89f658384","lessThan":"d96209626a29ea64666be98c30b30ac82e5f1be6","versionType":"git","status":"affected"}]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","programFiles":["drivers/usb/usbip/vudc_dev.c","drivers/usb/usbip/vudc_transfer.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","versions":[{"version":"4.7","status":"affected"},{"version":"0","lessThan":"4.7","versionType":"semver","status":"unaffected"},{"version":"5.10.259","lessThanOrEqual":"5.10.*","versionType":"semver","status":"unaffected"},{"version":"5.15.210","lessThanOrEqual":"5.15.*","versionType":"semver","status":"unaffected"},{"version":"6.1.176","lessThanOrEqual":"6.1.*","versionType":"semver","status":"unaffected"},{"version":"6.6.143","lessThanOrEqual":"6.6.*","versionType":"semver","status":"unaffected"},{"version":"6.12.93","lessThanOrEqual":"6.12.*","versionType":"semver","status":"unaffected"},{"version":"6.18.35","lessThanOrEqual":"6.18.*","versionType":"semver","status":"unaffected"},{"version":"7.0.12","lessThanOrEqual":"7.0.*","versionType":"semver","status":"unaffected"},{"version":"7.1","lessThanOrEqual":"*","versionType":"original_commit_for_fix","status":"unaffected"}]}]