{"id":"CVE-2026-63905","state":"PUBLISHED","title":"usbip: vudc: Fix use after free bug in vudc_remove due to race condition","description":"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's 2023 report of a use-after-free in\nvudc_remove(). The original thread stalled on Shuah Khan's request for\nruntime testing of the unplug/unbind path. This patch supplies that\ntesting and keeps Zheng's original fix shape.\n\nIn vudc_probe(), v_init_timer() binds udc->tr_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.","publishedAt":"2026-07-19T14:55:12.270Z","updatedAt":"2026-07-19T14:55:12.270Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"b6a0ca11186759ad7045d68a5447b1e89f658384","status":"affected","lessThan":"61704e5cf9cd7464b510eb606e7e2978b1160a64","versionType":"git"},{"version":"b6a0ca11186759ad7045d68a5447b1e89f658384","status":"affected","lessThan":"dcc1c90b28b28b7c493547506297e78653f81952","versionType":"git"},{"version":"b6a0ca11186759ad7045d68a5447b1e89f658384","status":"affected","lessThan":"1036ac6148995feaf486014d32bf26bf993c06a9","versionType":"git"},{"version":"b6a0ca11186759ad7045d68a5447b1e89f658384","status":"affected","lessThan":"a0638db2340ee053ab0450656a763fd111475e54","versionType":"git"},{"version":"b6a0ca11186759ad7045d68a5447b1e89f658384","status":"affected","lessThan":"d07ed707467ce05ea9c03412d0c5ee9d0fe386a6","versionType":"git"},{"version":"b6a0ca11186759ad7045d68a5447b1e89f658384","status":"affected","lessThan":"88d459e5b5a46da1ef9fd6f52d9439343edeec88","versionType":"git"},{"version":"b6a0ca11186759ad7045d68a5447b1e89f658384","status":"affected","lessThan":"207bf80362df3fce8ebc9723351dcb1bc6d9ed0f","versionType":"git"},{"version":"b6a0ca11186759ad7045d68a5447b1e89f658384","status":"affected","lessThan":"d96209626a29ea64666be98c30b30ac82e5f1be6","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/usb/usbip/vudc_dev.c","drivers/usb/usbip/vudc_transfer.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.7","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.7","versionType":"semver"},{"version":"5.10.259","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.210","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.176","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.143","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.93","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.35","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.12","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/usb/usbip/vudc_dev.c","drivers/usb/usbip/vudc_transfer.c"]}],"references":["https://git.kernel.org/stable/c/61704e5cf9cd7464b510eb606e7e2978b1160a64","https://git.kernel.org/stable/c/dcc1c90b28b28b7c493547506297e78653f81952","https://git.kernel.org/stable/c/1036ac6148995feaf486014d32bf26bf993c06a9","https://git.kernel.org/stable/c/a0638db2340ee053ab0450656a763fd111475e54","https://git.kernel.org/stable/c/d07ed707467ce05ea9c03412d0c5ee9d0fe386a6","https://git.kernel.org/stable/c/88d459e5b5a46da1ef9fd6f52d9439343edeec88","https://git.kernel.org/stable/c/207bf80362df3fce8ebc9723351dcb1bc6d9ed0f","https://git.kernel.org/stable/c/d96209626a29ea64666be98c30b30ac82e5f1be6"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/63xxx/CVE-2026-63905.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-63905","state":"PUBLISHED","datePublished":"2026-07-19T14:55:12.270Z","dateUpdated":"2026-07-19T14:55:12.270Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T07:54:57.020Z"},"containers":{"cna":{"title":"usbip: vudc: Fix use after free bug in vudc_remove due to race condition","descriptions":[{"lang":"en","value":"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's 2023 report of a use-after-free in\nvudc_remove(). The original thread stalled on Shuah Khan's request for\nruntime testing of the unplug/unbind path. This patch supplies that\ntesting and keeps Zheng's original fix shape.\n\nIn vudc_probe(), v_init_timer() binds udc->tr_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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"b6a0ca11186759ad7045d68a5447b1e89f658384","status":"affected","lessThan":"61704e5cf9cd7464b510eb606e7e2978b1160a64","versionType":"git"},{"version":"b6a0ca11186759ad7045d68a5447b1e89f658384","status":"affected","lessThan":"dcc1c90b28b28b7c493547506297e78653f81952","versionType":"git"},{"version":"b6a0ca11186759ad7045d68a5447b1e89f658384","status":"affected","lessThan":"1036ac6148995feaf486014d32bf26bf993c06a9","versionType":"git"},{"version":"b6a0ca11186759ad7045d68a5447b1e89f658384","status":"affected","lessThan":"a0638db2340ee053ab0450656a763fd111475e54","versionType":"git"},{"version":"b6a0ca11186759ad7045d68a5447b1e89f658384","status":"affected","lessThan":"d07ed707467ce05ea9c03412d0c5ee9d0fe386a6","versionType":"git"},{"version":"b6a0ca11186759ad7045d68a5447b1e89f658384","status":"affected","lessThan":"88d459e5b5a46da1ef9fd6f52d9439343edeec88","versionType":"git"},{"version":"b6a0ca11186759ad7045d68a5447b1e89f658384","status":"affected","lessThan":"207bf80362df3fce8ebc9723351dcb1bc6d9ed0f","versionType":"git"},{"version":"b6a0ca11186759ad7045d68a5447b1e89f658384","status":"affected","lessThan":"d96209626a29ea64666be98c30b30ac82e5f1be6","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/usb/usbip/vudc_dev.c","drivers/usb/usbip/vudc_transfer.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.7","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.7","versionType":"semver"},{"version":"5.10.259","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.210","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.176","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.143","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.93","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.35","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.12","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/usb/usbip/vudc_dev.c","drivers/usb/usbip/vudc_transfer.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/61704e5cf9cd7464b510eb606e7e2978b1160a64"},{"url":"https://git.kernel.org/stable/c/dcc1c90b28b28b7c493547506297e78653f81952"},{"url":"https://git.kernel.org/stable/c/1036ac6148995feaf486014d32bf26bf993c06a9"},{"url":"https://git.kernel.org/stable/c/a0638db2340ee053ab0450656a763fd111475e54"},{"url":"https://git.kernel.org/stable/c/d07ed707467ce05ea9c03412d0c5ee9d0fe386a6"},{"url":"https://git.kernel.org/stable/c/88d459e5b5a46da1ef9fd6f52d9439343edeec88"},{"url":"https://git.kernel.org/stable/c/207bf80362df3fce8ebc9723351dcb1bc6d9ed0f"},{"url":"https://git.kernel.org/stable/c/d96209626a29ea64666be98c30b30ac82e5f1be6"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-07-19T14:55:12.270Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"5.10.259"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"5.15.210"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"6.1.176"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"6.6.143"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"6.12.93"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"6.18.35"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"7.0.12"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"7.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}