{"id":"CVE-2026-89738","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-89738","summary":"usb: gadget: at91_udc: drain polled-VBUS timer/work before udc is freed","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nusb: gadget: at91_udc: drain polled-VBUS timer/work before udc is freed\n\nIn polled-VBUS mode (board.vbus_pin && board.vbus_polled), probe arms a\nself-restarting cycle: at91_vbus_timer() schedules vbus_timer_work, and\nat91_vbus_timer_work() calls at91_vbus_update() and re-arms the timer via\nmod_timer(). Both recover the same udc through container_of and dereference\nit on every iteration.\n\nNeither teardown path cancels this cycle. udc is devm-allocated, so it is\nfreed after at91udc_remove() returns, and is likewise freed when probe\nfails and devres runs. A timer callback or work item that is pending or\nrunning at either point dereferences the freed udc.\n\nAdd at91_udc_shutdown_vbus_timer() and call it from at91udc_remove() and\nfrom the usb_add_gadget_udc() failure path in probe; the remaining probe\nerror paths fail before the timer is armed. timer_shutdown_sync() waits\nfor a running callback and clears timer->function, which makes the work\nhandler's mod_timer() a permanent no-op; cancel_work_sync() then drains\nany pending or running work whose re-arm attempt now does nothing. The\ntimer must be shut down first, since cancelling the work alone would let\nthe timer re-queue it. The guard mirrors probe: in IRQ mode the timer and\nwork_struct are never initialized.\n\nThis does not require a fault; a normal driver unbind can interleave with\nan already queued work item.\n\nThis issue was found by an in-house static analysis tool.","published":"2026-09-11T19:46:45.898Z","modified":"2026-09-14T03:46:29.546593735Z","cvss":{"score":7.8,"severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"6.12.109"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/51a311eb97e91ce1aed3005cb71ccb2e30f8cce8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/557ef547d49ff5e6026a4d39bdd3113bd81d7688"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a2a602cb1e28d76a5398cec3fa21b0110385f501"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c27d13ce4bab80fbdf6523928071b6c24b37606c"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89738.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89738"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-14T03:46:29.546593735Z"}}