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ALSA: pcm: fix use-after-free on linked stream runtime in snd_pcm_drain()

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: ALSA: pcm: fix use-after-free on linked stream runtime in snd_pcm_drain() In the drain loop, the local variable 'runtime' is reassigned to a linked stream's runtime (runtime = s->runtime at line 2157). After releasing the stream lock at line 2169, the code accesses runtime->no_period_wakeup, runtime->rate, and runtime->buffer_size (lines 2170-2178) — all referencing the linked stream's runtime without any lock or refcount protecting its lifetime. A concurrent close() on the linked stream's fd triggers snd_pcm_release_substream() → snd_pcm_drop() → pcm_release_private() → snd_pcm_unlink() → snd_pcm_detach_substream() → kfree(runtime). No synchronization prevents kfree(runtime) from completing while the drain path dereferences the stale pointer. Fix by caching the needed runtime fields (no_period_wakeup, rate, buffer_size) into local variables while still holding the stream lock, and using the cached values after the lock is released.

Announced Source revision 1
Original source ↗

CVE-2026-43437

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-2026-43437

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": "f2b3614cefb61ee6046a0aaee503ee37f227d310",
        "lessThan": "9baee36e8c5443411c4629afabafaff8a46a23fd",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "f2b3614cefb61ee6046a0aaee503ee37f227d310",
        "lessThan": "f2cb2e0d27fb925c73a78f0ce7d6dbf68d3747c1",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "f2b3614cefb61ee6046a0aaee503ee37f227d310",
        "lessThan": "fc71f888994569f87d5bee20b1ac6c9c1e3a7a79",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "f2b3614cefb61ee6046a0aaee503ee37f227d310",
        "lessThan": "629cf09464cf98670996ea5c191dc9743e6f3f00",
        "versionType": "git"
      },
      {
        "status": "affected",
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        "lessThan": "ae8f8d30d334bad5b1b3cdb1eb8a0b771f55e432",
        "versionType": "git"
      },
      {
        "status": "affected",
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        "lessThan": "4a758e9a1f5ed722f83c4dd35f867fe811553bcb",
        "versionType": "git"
      },
      {
        "status": "affected",
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        "lessThan": "c2f64e05a0587a83ec42dbd6b7a7ded79b2ff694",
        "versionType": "git"
      },
      {
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        "lessThan": "9b1dbd69ba6f8f8c69bc7b77c2ce3b9c6ed05ba6",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "sound/core/pcm_native.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "3.0"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "3.0",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.10.253",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.220",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.167",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.130",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.78",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.19",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "6.19.9",
        "versionType": "semver",
        "lessThanOrEqual": "6.19.*"
      },
      {
        "status": "unaffected",
        "version": "7.0",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "sound/core/pcm_native.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-43437

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#40075 · Revision 1
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Publisher date
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