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

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Summary

CVECVE-2026-43437
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-08 15:16:56 UTC
Updated2026-05-11 08:16:14 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.000240000 probability, percentile 0.070400000 (date 2026-05-10)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected f2b3614cefb61ee6046a0aaee503ee37f227d310 9baee36e8c5443411c4629afabafaff8a46a23fd git Not specified
CNA Linux Linux affected f2b3614cefb61ee6046a0aaee503ee37f227d310 fc71f888994569f87d5bee20b1ac6c9c1e3a7a79 git Not specified
CNA Linux Linux affected f2b3614cefb61ee6046a0aaee503ee37f227d310 629cf09464cf98670996ea5c191dc9743e6f3f00 git Not specified
CNA Linux Linux affected f2b3614cefb61ee6046a0aaee503ee37f227d310 ae8f8d30d334bad5b1b3cdb1eb8a0b771f55e432 git Not specified
CNA Linux Linux affected f2b3614cefb61ee6046a0aaee503ee37f227d310 4a758e9a1f5ed722f83c4dd35f867fe811553bcb git Not specified
CNA Linux Linux affected f2b3614cefb61ee6046a0aaee503ee37f227d310 c2f64e05a0587a83ec42dbd6b7a7ded79b2ff694 git Not specified
CNA Linux Linux affected f2b3614cefb61ee6046a0aaee503ee37f227d310 9b1dbd69ba6f8f8c69bc7b77c2ce3b9c6ed05ba6 git Not specified
CNA Linux Linux affected 3.0 Not specified
CNA Linux Linux unaffected 3.0 semver Not specified
CNA Linux Linux unaffected 5.10.253 5.10.* semver Not specified
CNA Linux Linux unaffected 6.1.167 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.130 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.78 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.19 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19.9 6.19.* semver Not specified
CNA Linux Linux unaffected 7.0 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/629cf09464cf98670996ea5c191dc9743e6f3f00 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/9b1dbd69ba6f8f8c69bc7b77c2ce3b9c6ed05ba6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/ae8f8d30d334bad5b1b3cdb1eb8a0b771f55e432 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/c2f64e05a0587a83ec42dbd6b7a7ded79b2ff694 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/9baee36e8c5443411c4629afabafaff8a46a23fd 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/4a758e9a1f5ed722f83c4dd35f867fe811553bcb 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/fc71f888994569f87d5bee20b1ac6c9c1e3a7a79 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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