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CVE-2026-89738— usb: gadget: at91_udc: drain polled-VBUS timer/work before udc is freed

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

在 Linux 内核中，以下漏洞已得到修复： usb: gadget: at91_udc：在 udc 被释放前，先排空（drain）轮询式 VBUS 的定时器/工作队列 在轮询式 VBUS 模式（即 ）下， 函数会启动一个自我重启的循环： 会调度 ，而 会调用 ，并通过 重新武装定时器。这两个函数都通过 恢复同一个 对象，并在每次迭代中对其进行解引用。 然而，在卸载（teardown）路径中，并没有取消这个循环。由于 是通过 分配的，因此当 返回后，或者当 失败并执行 时， 会被释放。如果此时有定时器回调或工作项仍

AI Predicted 7.0 Difficulty: Moderate

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux 4037242c4f5ff77afe61bf07ca1e8a99490219e5< a2a602cb1e28d76a5398cec3fa21b0110385f501 affected
4037242c4f5ff77afe61bf07ca1e8a99490219e5< 51a311eb97e91ce1aed3005cb71ccb2e30f8cce8 affected
4037242c4f5ff77afe61bf07ca1e8a99490219e5< 557ef547d49ff5e6026a4d39bdd3113bd81d7688 affected
4037242c4f5ff77afe61bf07ca1e8a99490219e5< c27d13ce4bab80fbdf6523928071b6c24b37606c affected
2.6.36 affected
< 2.6.36 unaffected
6.12.109≤ 6.12.* unaffected
6.18.50≤ 6.18.* unaffected
… +2 more rows
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I. Basic Information for CVE-2026-89738

Vulnerability Information
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Vulnerability Title
usb: gadget: at91_udc: drain polled-VBUS timer/work before udc is freed
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: usb: gadget: at91_udc: drain polled-VBUS timer/work before udc is freed In polled-VBUS mode (board.vbus_pin && board.vbus_polled), probe arms a self-restarting cycle: at91_vbus_timer() schedules vbus_timer_work, and at91_vbus_timer_work() calls at91_vbus_update() and re-arms the timer via mod_timer(). Both recover the same udc through container_of and dereference it on every iteration. Neither teardown path cancels this cycle. udc is devm-allocated, so it is freed after at91udc_remove() returns, and is likewise freed when probe fails and devres runs. A timer callback or work item that is pending or running at either point dereferences the freed udc. Add at91_udc_shutdown_vbus_timer() and call it from at91udc_remove() and from the usb_add_gadget_udc() failure path in probe; the remaining probe error paths fail before the timer is armed. timer_shutdown_sync() waits for a running callback and clears timer->function, which makes the work handler's mod_timer() a permanent no-op; cancel_work_sync() then drains any pending or running work whose re-arm attempt now does nothing. The timer must be shut down first, since cancelling the work alone would let the timer re-queue it. The guard mirrors probe: in IRQ mode the timer and work_struct are never initialized. This does not require a fault; a normal driver unbind can interleave with an already queued work item. This issue was found by an in-house static analysis tool.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 4037242c4f5ff77afe61bf07ca1e8a99490219e5 ~ a2a602cb1e28d76a5398cec3fa21b0110385f501 -
Linux Linux 2.6.36 -

II. Public POCs for CVE-2026-89738

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III. Intelligence Information for CVE-2026-89738

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Other References for CVE-2026-89738 (4)

Same Patch Batch · Linux · 2026-09-11 · 431 CVEs total

CVE-2026-89491 ocfs2: cluster: don't sleep while holding o2hb_live_lock in o2hb_region_pin()
CVE-2026-89477 sctp: fix NULL deref on untransmitted RECONF completion
CVE-2026-89478 sctp: drop a chunk if its transport was removed
CVE-2026-89479 sctp: stop processing a packet once its association is deleted
CVE-2026-89480 nvme-tcp: reject a read that transferred too few bytes
CVE-2026-89482 nvme-tcp: do not accept C2HData based on blk_rq_payload_bytes() alone
CVE-2026-89481 nvme-tcp: fix host memory disclosure on R2T for a read command
CVE-2026-89483 nvme: zero the discard fallback page
CVE-2026-89484 lockd: fix NULL dereference on lockowner allocation failure
CVE-2026-89485 lockd: pin next file across nlm_inspect_file lock-drop
CVE-2026-89486 ipmi: Fix use-after-free of cmd_rcvr in _ipmi_destroy_user()
CVE-2026-89487 openvswitch: only skb_tx_error() a packet we are about to drop
CVE-2026-89488 openvswitch: Fix CT limit teardown use-after-free
CVE-2026-89489 openrisc: fix arbitrary kernel memory access via or1k_atomic syscall
CVE-2026-89500 ring-buffer: Make cpu_buffer::free_page a buffer_data_read_page
CVE-2026-89497 orangefs: skip leading spaces before parsing client debug masks
CVE-2026-89498 orangefs: fix double-free of trailer_buf on readdir copy failure
CVE-2026-89499 ring-buffer: Stop remote reader update when page swap fails
CVE-2026-89496 ocfs2: always run deallocs on copy-on-write completion
CVE-2026-89501 ring-buffer: Hold cpu_buffer::lock when resizing a subbuf

Showing top 20 of 431 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-89738

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