{"api_version":"1","generated_at":"2026-05-13T12:03:26+00:00","cve":"CVE-2026-31726","urls":{"html":"https://cve.report/CVE-2026-31726","api":"https://cve.report/api/cve/CVE-2026-31726.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-31726","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-31726"},"summary":{"title":"usb: gadget: uvc: fix NULL pointer dereference during unbind race","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nusb: gadget: uvc: fix NULL pointer dereference during unbind race\n\nCommit b81ac4395bbe (\"usb: gadget: uvc: allow for application to cleanly\nshutdown\") introduced two stages of synchronization waits totaling 1500ms\nin uvc_function_unbind() to prevent several types of kernel panics.\nHowever, this timing-based approach is insufficient during power\nmanagement (PM) transitions.\n\nWhen the PM subsystem starts freezing user space processes, the\nwait_event_interruptible_timeout() is aborted early, which allows the\nunbind thread to proceed and nullify the gadget pointer\n(cdev->gadget = NULL):\n\n[  814.123447][  T947] configfs-gadget.g1 gadget.0: uvc: uvc_function_unbind()\n[  814.178583][ T3173] PM: suspend entry (deep)\n[  814.192487][ T3173] Freezing user space processes\n[  814.197668][  T947] configfs-gadget.g1 gadget.0: uvc: uvc_function_unbind no clean disconnect, wait for release\n\nWhen the PM subsystem resumes or aborts the suspend and tasks are\nrestarted, the V4L2 release path is executed and attempts to access the\nalready nullified gadget pointer, triggering a kernel panic:\n\n[  814.292597][    C0] PM: pm_system_irq_wakeup: 479 triggered dhdpcie_host_wake\n[  814.386727][ T3173] Restarting tasks ...\n[  814.403522][ T4558] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000030\n[  814.404021][ T4558] pc : usb_gadget_deactivate+0x14/0xf4\n[  814.404031][ T4558] lr : usb_function_deactivate+0x54/0x94\n[  814.404078][ T4558] Call trace:\n[  814.404080][ T4558]  usb_gadget_deactivate+0x14/0xf4\n[  814.404083][ T4558]  usb_function_deactivate+0x54/0x94\n[  814.404087][ T4558]  uvc_function_disconnect+0x1c/0x5c\n[  814.404092][ T4558]  uvc_v4l2_release+0x44/0xac\n[  814.404095][ T4558]  v4l2_release+0xcc/0x130\n\nAddress the race condition and NULL pointer dereference by:\n\n1. State Synchronization (flag + mutex)\nIntroduce a 'func_unbound' flag in struct uvc_device. This allows\nuvc_function_disconnect() to safely skip accessing the nullified\ncdev->gadget pointer. As suggested by Alan Stern, this flag is protected\nby a new mutex (uvc->lock) to ensure proper memory ordering and prevent\ninstruction reordering or speculative loads. This mutex is also used to\nprotect 'func_connected' for consistent state management.\n\n2. Explicit Synchronization (completion)\nUse a completion to synchronize uvc_function_unbind() with the\nuvc_vdev_release() callback. This prevents Use-After-Free (UAF) by\nensuring struct uvc_device is freed after all video device resources\nare released.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-05-01 15:16:35","updated_at":"2026-05-07 16:26:18"},"problem_types":["CWE-476"],"metrics":[{"version":"3.1","source":"nvd@nist.gov","type":"Primary","score":"5.5","severity":"MEDIUM","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","baseScore":5.5,"baseSeverity":"MEDIUM","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"}}],"references":[{"url":"https://git.kernel.org/stable/c/1aa9356881ee4ed414bf72d0c56d915492cb5345","name":"https://git.kernel.org/stable/c/1aa9356881ee4ed414bf72d0c56d915492cb5345","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/0c00ec409d7b2bce3fcac73188b79a141db7cfda","name":"https://git.kernel.org/stable/c/0c00ec409d7b2bce3fcac73188b79a141db7cfda","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/8a1128d604c360eca135f15b882b70256a522145","name":"https://git.kernel.org/stable/c/8a1128d604c360eca135f15b882b70256a522145","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/c78e463ee134b4669579d453c81ae00795e4c19a","name":"https://git.kernel.org/stable/c/c78e463ee134b4669579d453c81ae00795e4c19a","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/0587de744615628c38e33ddc1601160a5ea8c50a","name":"https://git.kernel.org/stable/c/0587de744615628c38e33ddc1601160a5ea8c50a","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/d92d1532e05b1b31d36d48765e43bf73d793d19f","name":"https://git.kernel.org/stable/c/d92d1532e05b1b31d36d48765e43bf73d793d19f","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/eba2936bbe6b752a31725a9eb5c674ecbf21ee7d","name":"https://git.kernel.org/stable/c/eba2936bbe6b752a31725a9eb5c674ecbf21ee7d","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/c038ba56b92e410d1caec22b2dc68780a0b42091","name":"https://git.kernel.org/stable/c/c038ba56b92e410d1caec22b2dc68780a0b42091","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-31726","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31726","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1444e0568bc2c70868e7b8da5b46fc2252acc3f5 0c00ec409d7b2bce3fcac73188b79a141db7cfda git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4962e5a2f301d24953f17d6748d986e21566abe1 d92d1532e05b1b31d36d48765e43bf73d793d19f git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected b81ac4395bbeaf36e078dea1a48c02dd97b76235 0587de744615628c38e33ddc1601160a5ea8c50a git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected b81ac4395bbeaf36e078dea1a48c02dd97b76235 c78e463ee134b4669579d453c81ae00795e4c19a git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 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semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.10.253 5.10.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15.203 5.15.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.168 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.134 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.81 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.22 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.19.12 6.19.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[{"cve_year":"2026","cve_id":"31726","vulnerable":"1","versionEndIncluding":"","cpe1":"cpe","cpe2":"2.3","cpe3":"o","cpe4":"linux","cpe5":"linux_kernel","cpe6":"*","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"*","cpe11":"*","cpe12":"*","cpe13":"*"}],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"31726","cve":"CVE-2026-31726","epss":"0.000240000","percentile":"0.068060000","score_date":"2026-05-05","updated_at":"2026-05-06 00:08:10"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["drivers/usb/gadget/function/f_uvc.c","drivers/usb/gadget/function/uvc.h","drivers/usb/gadget/function/uvc_v4l2.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"0c00ec409d7b2bce3fcac73188b79a141db7cfda","status":"affected","version":"1444e0568bc2c70868e7b8da5b46fc2252acc3f5","versionType":"git"},{"lessThan":"d92d1532e05b1b31d36d48765e43bf73d793d19f","status":"affected","version":"4962e5a2f301d24953f17d6748d986e21566abe1","versionType":"git"},{"lessThan":"0587de744615628c38e33ddc1601160a5ea8c50a","status":"affected","version":"b81ac4395bbeaf36e078dea1a48c02dd97b76235","versionType":"git"},{"lessThan":"c78e463ee134b4669579d453c81ae00795e4c19a","status":"affected","version":"b81ac4395bbeaf36e078dea1a48c02dd97b76235","versionType":"git"},{"lessThan":"8a1128d604c360eca135f15b882b70256a522145","status":"affected","version":"b81ac4395bbeaf36e078dea1a48c02dd97b76235","versionType":"git"},{"lessThan":"1aa9356881ee4ed414bf72d0c56d915492cb5345","status":"affected","version":"b81ac4395bbeaf36e078dea1a48c02dd97b76235","versionType":"git"},{"lessThan":"c038ba56b92e410d1caec22b2dc68780a0b42091","status":"affected","version":"b81ac4395bbeaf36e078dea1a48c02dd97b76235","versionType":"git"},{"lessThan":"eba2936bbe6b752a31725a9eb5c674ecbf21ee7d","status":"affected","version":"b81ac4395bbeaf36e078dea1a48c02dd97b76235","versionType":"git"},{"status":"affected","version":"e10735ce87502b07e171727e574afdd6c0890a08","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["drivers/usb/gadget/function/f_uvc.c","drivers/usb/gadget/function/uvc.h","drivers/usb/gadget/function/uvc_v4l2.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"5.18"},{"lessThan":"5.18","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"5.10.*","status":"unaffected","version":"5.10.253","versionType":"semver"},{"lessThanOrEqual":"5.15.*","status":"unaffected","version":"5.15.203","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.168","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.134","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.81","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.22","versionType":"semver"},{"lessThanOrEqual":"6.19.*","status":"unaffected","version":"6.19.12","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.0","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.10.253","versionStartIncluding":"5.10.117","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.15.203","versionStartIncluding":"5.15.41","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.168","versionStartIncluding":"5.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.134","versionStartIncluding":"5.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.81","versionStartIncluding":"5.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.22","versionStartIncluding":"5.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.19.12","versionStartIncluding":"5.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.0","versionStartIncluding":"5.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.17.9","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nusb: gadget: uvc: fix NULL pointer dereference during unbind race\n\nCommit b81ac4395bbe (\"usb: gadget: uvc: allow for application to cleanly\nshutdown\") introduced two stages of synchronization waits totaling 1500ms\nin uvc_function_unbind() to prevent several types of kernel panics.\nHowever, this timing-based approach is insufficient during power\nmanagement (PM) transitions.\n\nWhen the PM subsystem starts freezing user space processes, the\nwait_event_interruptible_timeout() is aborted early, which allows the\nunbind thread to proceed and nullify the gadget pointer\n(cdev->gadget = NULL):\n\n[  814.123447][  T947] configfs-gadget.g1 gadget.0: uvc: uvc_function_unbind()\n[  814.178583][ T3173] PM: suspend entry (deep)\n[  814.192487][ T3173] Freezing user space processes\n[  814.197668][  T947] configfs-gadget.g1 gadget.0: uvc: uvc_function_unbind no clean disconnect, wait for release\n\nWhen the PM subsystem resumes or aborts the suspend and tasks are\nrestarted, the V4L2 release path is executed and attempts to access the\nalready nullified gadget pointer, triggering a kernel panic:\n\n[  814.292597][    C0] PM: pm_system_irq_wakeup: 479 triggered dhdpcie_host_wake\n[  814.386727][ T3173] Restarting tasks ...\n[  814.403522][ T4558] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000030\n[  814.404021][ T4558] pc : usb_gadget_deactivate+0x14/0xf4\n[  814.404031][ T4558] lr : usb_function_deactivate+0x54/0x94\n[  814.404078][ T4558] Call trace:\n[  814.404080][ T4558]  usb_gadget_deactivate+0x14/0xf4\n[  814.404083][ T4558]  usb_function_deactivate+0x54/0x94\n[  814.404087][ T4558]  uvc_function_disconnect+0x1c/0x5c\n[  814.404092][ T4558]  uvc_v4l2_release+0x44/0xac\n[  814.404095][ T4558]  v4l2_release+0xcc/0x130\n\nAddress the race condition and NULL pointer dereference by:\n\n1. State Synchronization (flag + mutex)\nIntroduce a 'func_unbound' flag in struct uvc_device. This allows\nuvc_function_disconnect() to safely skip accessing the nullified\ncdev->gadget pointer. As suggested by Alan Stern, this flag is protected\nby a new mutex (uvc->lock) to ensure proper memory ordering and prevent\ninstruction reordering or speculative loads. This mutex is also used to\nprotect 'func_connected' for consistent state management.\n\n2. Explicit Synchronization (completion)\nUse a completion to synchronize uvc_function_unbind() with the\nuvc_vdev_release() callback. This prevents Use-After-Free (UAF) by\nensuring struct uvc_device is freed after all video device resources\nare released."}],"providerMetadata":{"dateUpdated":"2026-05-01T14:14:26.882Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/0c00ec409d7b2bce3fcac73188b79a141db7cfda"},{"url":"https://git.kernel.org/stable/c/d92d1532e05b1b31d36d48765e43bf73d793d19f"},{"url":"https://git.kernel.org/stable/c/0587de744615628c38e33ddc1601160a5ea8c50a"},{"url":"https://git.kernel.org/stable/c/c78e463ee134b4669579d453c81ae00795e4c19a"},{"url":"https://git.kernel.org/stable/c/8a1128d604c360eca135f15b882b70256a522145"},{"url":"https://git.kernel.org/stable/c/1aa9356881ee4ed414bf72d0c56d915492cb5345"},{"url":"https://git.kernel.org/stable/c/c038ba56b92e410d1caec22b2dc68780a0b42091"},{"url":"https://git.kernel.org/stable/c/eba2936bbe6b752a31725a9eb5c674ecbf21ee7d"}],"title":"usb: gadget: uvc: fix NULL pointer dereference during unbind race","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-31726","datePublished":"2026-05-01T14:14:26.882Z","dateReserved":"2026-03-09T15:48:24.134Z","dateUpdated":"2026-05-01T14:14:26.882Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-05-01 15:16:35","lastModifiedDate":"2026-05-07 16:26:18","problem_types":["CWE-476"],"metrics":{"cvssMetricV31":[{"source":"nvd@nist.gov","type":"Primary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","baseScore":5.5,"baseSeverity":"MEDIUM","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":3.6}]},"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10.117","versionEndExcluding":"5.10.253","matchCriteriaId":"3107A7FD-A692-4C8A-AEB6-F0D2F2662FB9"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15.41","versionEndExcluding":"5.15.203","matchCriteriaId":"10AB2B1C-2087-4373-A0B0-DF5A1661F0BA"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.18","versionEndExcluding":"6.1.168","matchCriteriaId":"BA6F49FC-BA51-4640-976D-34617774A48C"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.2","versionEndExcluding":"6.6.134","matchCriteriaId":"F56F925B-BAF8-4F4B-B62F-1496AF19A307"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.7","versionEndExcluding":"6.12.81","matchCriteriaId":"6EF80433-B33B-43C5-8E64-0FA7B8DCE1BC"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.13","versionEndExcluding":"6.18.22","matchCriteriaId":"C9DF8BCE-36D3-475D-9D21-19E4F02F9029"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.19","versionEndExcluding":"6.19.12","matchCriteriaId":"0A2B9540-02D5-41B4-B16A-82AF66FD4F36"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*","matchCriteriaId":"F253B622-8837-4245-BCE5-A7BF8FC76A16"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*","matchCriteriaId":"4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*","matchCriteriaId":"F666C8D8-6538-46D4-B318-87610DE64C34"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*","matchCriteriaId":"02259FDA-961B-47BC-AE7F-93D7EC6E90C2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*","matchCriteriaId":"58A9FEFF-C040-420D-8F0A-BFDAAA1DF258"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*","matchCriteriaId":"1D2315C0-D46F-4F85-9754-F9E5E11374A6"}]}]}]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"31726","Ordinal":"1","Title":"usb: gadget: uvc: fix NULL pointer dereference during unbind rac","CVE":"CVE-2026-31726","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"31726","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nusb: gadget: uvc: fix NULL pointer dereference during unbind race\n\nCommit b81ac4395bbe (\"usb: gadget: uvc: allow for application to cleanly\nshutdown\") introduced two stages of synchronization waits totaling 1500ms\nin uvc_function_unbind() to prevent several types of kernel panics.\nHowever, this timing-based approach is insufficient during power\nmanagement (PM) transitions.\n\nWhen the PM subsystem starts freezing user space processes, the\nwait_event_interruptible_timeout() is aborted early, which allows the\nunbind thread to proceed and nullify the gadget pointer\n(cdev->gadget = NULL):\n\n[  814.123447][  T947] configfs-gadget.g1 gadget.0: uvc: uvc_function_unbind()\n[  814.178583][ T3173] PM: suspend entry (deep)\n[  814.192487][ T3173] Freezing user space processes\n[  814.197668][  T947] configfs-gadget.g1 gadget.0: uvc: uvc_function_unbind no clean disconnect, wait for release\n\nWhen the PM subsystem resumes or aborts the suspend and tasks are\nrestarted, the V4L2 release path is executed and attempts to access the\nalready nullified gadget pointer, triggering a kernel panic:\n\n[  814.292597][    C0] PM: pm_system_irq_wakeup: 479 triggered dhdpcie_host_wake\n[  814.386727][ T3173] Restarting tasks ...\n[  814.403522][ T4558] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000030\n[  814.404021][ T4558] pc : usb_gadget_deactivate+0x14/0xf4\n[  814.404031][ T4558] lr : usb_function_deactivate+0x54/0x94\n[  814.404078][ T4558] Call trace:\n[  814.404080][ T4558]  usb_gadget_deactivate+0x14/0xf4\n[  814.404083][ T4558]  usb_function_deactivate+0x54/0x94\n[  814.404087][ T4558]  uvc_function_disconnect+0x1c/0x5c\n[  814.404092][ T4558]  uvc_v4l2_release+0x44/0xac\n[  814.404095][ T4558]  v4l2_release+0xcc/0x130\n\nAddress the race condition and NULL pointer dereference by:\n\n1. State Synchronization (flag + mutex)\nIntroduce a 'func_unbound' flag in struct uvc_device. This allows\nuvc_function_disconnect() to safely skip accessing the nullified\ncdev->gadget pointer. As suggested by Alan Stern, this flag is protected\nby a new mutex (uvc->lock) to ensure proper memory ordering and prevent\ninstruction reordering or speculative loads. This mutex is also used to\nprotect 'func_connected' for consistent state management.\n\n2. Explicit Synchronization (completion)\nUse a completion to synchronize uvc_function_unbind() with the\nuvc_vdev_release() callback. This prevents Use-After-Free (UAF) by\nensuring struct uvc_device is freed after all video device resources\nare released.","Type":"Description","Title":"usb: gadget: uvc: fix NULL pointer dereference during unbind rac"}]}}}