GHSA-VPXX-F4PR-JGGR
Vulnerability from github – Published: 2026-07-19 18:31 – Updated: 2026-07-19 18:31In 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.
{
"affected": [],
"aliases": [
"CVE-2026-63905"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-19T16:17:08Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nusbip: vudc: Fix use after free bug in vudc_remove due to race condition\n\nThis patch follows up Zheng Wang\u0027s 2023 report of a use-after-free in\nvudc_remove(). The original thread stalled on Shuah Khan\u0027s request for\nruntime testing of the unplug/unbind path. This patch supplies that\ntesting and keeps Zheng\u0027s original fix shape.\n\nIn vudc_probe(), v_init_timer() binds udc-\u003etr_timer.timer to v_timer().\nusbip_sockfd_store() starts the timer via v_start_timer()/v_kick_timer().\nvudc_remove() can then free the containing struct vudc while the timer is\nstill pending or executing.\n\nKASAN confirms the race on an unpatched x86_64 QEMU guest with\nCONFIG_KASAN=y, CONFIG_USBIP_VUDC=y, CONFIG_USB_ZERO=y, and a tight loop\nthat repeatedly writes a socket fd to usbip_sockfd, closes the socket\npair, and unbinds/rebinds usbip-vudc.0:\n\n BUG: KASAN: slab-use-after-free in __run_timer_base.part.0+0x8ba/0x8e0\n Write of size 8 at addr ffff888001b80740 by task trigger_and_unb/239\n Allocated by task 239:\n vudc_probe+0x4d/0xaa0\n Freed by task 239:\n kfree+0x18f/0x520\n device_release_driver_internal+0x388/0x540\n unbind_store+0xd9/0x100\n\nThis lands in the timer core rather than v_timer() itself because the\nembedded timer_list is being walked after its containing struct vudc has\nalready been freed. The underlying lifetime bug is the same one Zheng\nreported.\n\nWith v_stop_timer() called from vudc_remove() and the timer deleted\nsynchronously, the same harness completed 5000 bind/unbind iterations\nwith no KASAN report.",
"id": "GHSA-vpxx-f4pr-jggr",
"modified": "2026-07-19T18:31:45Z",
"published": "2026-07-19T18:31:45Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-63905"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1036ac6148995feaf486014d32bf26bf993c06a9"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/207bf80362df3fce8ebc9723351dcb1bc6d9ed0f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/61704e5cf9cd7464b510eb606e7e2978b1160a64"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/88d459e5b5a46da1ef9fd6f52d9439343edeec88"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a0638db2340ee053ab0450656a763fd111475e54"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d07ed707467ce05ea9c03412d0c5ee9d0fe386a6"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d96209626a29ea64666be98c30b30ac82e5f1be6"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/dcc1c90b28b28b7c493547506297e78653f81952"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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