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usb: gadget: at91_udc: drain polled-VBUS timer/work before udc is freed

Type: advisorySource: Official CVE List1 source record

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

Announced Source revision 1
Original source ↗

CVE-2026-89738

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-89738

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "4037242c4f5ff77afe61bf07ca1e8a99490219e5",
        "lessThan": "723d73b245843d4fff4c3f42e857c78c2b2d414e",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4037242c4f5ff77afe61bf07ca1e8a99490219e5",
        "lessThan": "a2a602cb1e28d76a5398cec3fa21b0110385f501",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4037242c4f5ff77afe61bf07ca1e8a99490219e5",
        "lessThan": "51a311eb97e91ce1aed3005cb71ccb2e30f8cce8",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4037242c4f5ff77afe61bf07ca1e8a99490219e5",
        "lessThan": "557ef547d49ff5e6026a4d39bdd3113bd81d7688",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4037242c4f5ff77afe61bf07ca1e8a99490219e5",
        "lessThan": "c27d13ce4bab80fbdf6523928071b6c24b37606c",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "drivers/usb/gadget/udc/at91_udc.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "2.6.36"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "2.6.36",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.6.160",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.109",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.50",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.2.4",
        "versionType": "semver",
        "lessThanOrEqual": "7.2.*"
      },
      {
        "status": "unaffected",
        "version": "7.3",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "drivers/usb/gadget/udc/at91_udc.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-89738

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#46715 · Revision 1
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