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

{
  "id": "e9ae01539280c6f2cf213f9f0fc3bc9c10f2205fd587caf92e29af4edd002e48",
  "url": "https://osv.dev/vulnerability/CVE-2026-63905",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "usbip: vudc: Fix use after free bug in vudc_remove due to race condition",
    "summary": "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 harnes",
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      "modified": "2026-11-01T02:30:21.704985740Z",
      "provider": "osv",
      "references": [
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        "https://git.kernel.org/stable/c/207bf80362df3fce8ebc9723351dcb1bc6d9ed0f",
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        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63905.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-63905",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
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    "security_relevant": true,
    "severity_evidence": null
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  "source_id": "core-osv",
  "document_id": 489224,
  "published_at": "2026-07-19T14:55:12.27+00:00"
}