From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-43437: ALSA: pcm: fix use-after-free on linked stream runtime in snd_pcm_drain()
Date: Fri, 8 May 2026 16:22:46 +0200 [thread overview]
Message-ID: <2026050853-CVE-2026-43437-be27@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
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.
The Linux kernel CVE team has assigned CVE-2026-43437 to this issue.
Affected and fixed versions
===========================
Issue introduced in 3.0 with commit f2b3614cefb61ee6046a0aaee503ee37f227d310 and fixed in 5.10.253 with commit 9baee36e8c5443411c4629afabafaff8a46a23fd
Issue introduced in 3.0 with commit f2b3614cefb61ee6046a0aaee503ee37f227d310 and fixed in 6.1.167 with commit fc71f888994569f87d5bee20b1ac6c9c1e3a7a79
Issue introduced in 3.0 with commit f2b3614cefb61ee6046a0aaee503ee37f227d310 and fixed in 6.6.130 with commit 629cf09464cf98670996ea5c191dc9743e6f3f00
Issue introduced in 3.0 with commit f2b3614cefb61ee6046a0aaee503ee37f227d310 and fixed in 6.12.78 with commit ae8f8d30d334bad5b1b3cdb1eb8a0b771f55e432
Issue introduced in 3.0 with commit f2b3614cefb61ee6046a0aaee503ee37f227d310 and fixed in 6.18.19 with commit 4a758e9a1f5ed722f83c4dd35f867fe811553bcb
Issue introduced in 3.0 with commit f2b3614cefb61ee6046a0aaee503ee37f227d310 and fixed in 6.19.9 with commit c2f64e05a0587a83ec42dbd6b7a7ded79b2ff694
Issue introduced in 3.0 with commit f2b3614cefb61ee6046a0aaee503ee37f227d310 and fixed in 7.0 with commit 9b1dbd69ba6f8f8c69bc7b77c2ce3b9c6ed05ba6
Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.
Unaffected versions might change over time as fixes are backported to
older supported kernel versions. The official CVE entry at
https://cve.org/CVERecord/?id=CVE-2026-43437
will be updated if fixes are backported, please check that for the most
up to date information about this issue.
Affected files
==============
The file(s) affected by this issue are:
sound/core/pcm_native.c
Mitigation
==========
The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes. Individual
changes are never tested alone, but rather are part of a larger kernel
release. Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all. If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
https://git.kernel.org/stable/c/9baee36e8c5443411c4629afabafaff8a46a23fd
https://git.kernel.org/stable/c/fc71f888994569f87d5bee20b1ac6c9c1e3a7a79
https://git.kernel.org/stable/c/629cf09464cf98670996ea5c191dc9743e6f3f00
https://git.kernel.org/stable/c/ae8f8d30d334bad5b1b3cdb1eb8a0b771f55e432
https://git.kernel.org/stable/c/4a758e9a1f5ed722f83c4dd35f867fe811553bcb
https://git.kernel.org/stable/c/c2f64e05a0587a83ec42dbd6b7a7ded79b2ff694
https://git.kernel.org/stable/c/9b1dbd69ba6f8f8c69bc7b77c2ce3b9c6ed05ba6
reply other threads:[~2026-05-08 14:25 UTC|newest]
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