CVE-2026-43437
Description
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.
How to fix
- linux linux_kernel5.10.253, 6.1.167, 6.6.130, 6.12.78, 6.18.19, 6.19.9 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| linux linux_kernel | 3.0 ≤ v < 5.10.253, 5.11 ≤ v < 6.1.167, 6.2 ≤ v < 6.6.130, 6.7 ≤ v < 6.12.78, 6.13 ≤ v < 6.18.19, 6.19 ≤ v < 6.19.9, 7.0 | 5.10.253, 6.1.167, 6.6.130, 6.12.78, 6.18.19, 6.19.9 |
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