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ALSA: timer: Clear SNDRV_TIMER_IFLG_DEAD once the close completes

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: ALSA: timer: Clear SNDRV_TIMER_IFLG_DEAD once the close completes snd_timer_close_locked() marks an instance with SNDRV_TIMER_IFLG_DEAD and returns early when the flag is already set, but the flag is never cleared again. A completed close ends in remove_slave_links(), which leaves timeri->timer NULL, so a second close is already harmless through the timer == NULL path; the early return can only be reached by an instance that was opened again in between. For such an instance the close unlinks nothing, so snd_timer_instance_free() frees an object that is still on timer->open_list_head, still on snd_timer_master_list if it was opened with a slave key, still owns any adopted slaves, and still holds its timer and module references. snd_seq_timer_open() reopens an instance exactly like that: it retries its fallback open on the same object after a failure that has already run snd_timer_close_locked() internally. An unprivileged user with access to /dev/snd/timer and /dev/snd/seq can force that failure, since snd_timer_check_master() returns -EBUSY when a pending slave matches the new master's (slave_class, slave_id) key and the target timer has reached max_instances, and SNDRV_TIMER_IOCTL_SELECT with dev_class = SNDRV_TIMER_CLASS_SLAVE keeps the caller-supplied dev_sclass, so a sequencer queue's key can be forged. The freed instance is afterwards dereferenced by any further snd_timer_open() on that timer, by snd_tim

Announced Source revision 1
Original source ↗

CVE-2026-74503

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-2026-74503

Linux

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

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
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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": "586b219a22b1032b28b8bd356b963276c5e5bf53",
        "lessThan": "bb016091010ec401a06e6bdace0cd944ee03d371",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "f46093dd22969037beb1fce2e043f3236be41c92",
        "lessThan": "a26a2e52736f9e39843ca66a2e1ce6bf1adbcd1e",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "da3039e91d1f835874ed6e9a33ea19ee80c2cb92",
        "lessThan": "0c561fab50991df10b1e4daca25886c34a2a9c07",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "da3039e91d1f835874ed6e9a33ea19ee80c2cb92",
        "lessThan": "c2744d5f3aea474513fd2298daecb94a952ce441",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "60e73ab87b84bbd6bd7ddd1d16019a3a3705ab8f",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "6.12.94",
        "lessThan": "6.12.103",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "6.18.36",
        "lessThan": "6.18.44",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "7.0.13",
        "lessThan": "7.1",
        "versionType": "semver"
      }
    ],
    "programFiles": [
      "sound/core/timer.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "7.1"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "7.1",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.12.103",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.44",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.1.8",
        "versionType": "semver",
        "lessThanOrEqual": "7.1.*"
      },
      {
        "status": "unaffected",
        "version": "7.2",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "sound/core/timer.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-74503

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#33183 · Revision 1
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Publisher date
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