GHSA-5CW4-RFP6-XJFX
Vulnerability from github – Published: 2026-05-08 15:31 – Updated: 2026-09-02 15:33In 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.
{
"affected": [],
"aliases": [
"CVE-2026-43437"
],
"database_specific": {
"cwe_ids": [
"CWE-416"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-05-08T15:16:56Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: pcm: fix use-after-free on linked stream runtime in snd_pcm_drain()\n\nIn the drain loop, the local variable \u0027runtime\u0027 is reassigned to a\nlinked stream\u0027s runtime (runtime = s-\u003eruntime at line 2157). After\nreleasing the stream lock at line 2169, the code accesses\nruntime-\u003eno_period_wakeup, runtime-\u003erate, and runtime-\u003ebuffer_size\n(lines 2170-2178) \u2014 all referencing the linked stream\u0027s runtime without\nany lock or refcount protecting its lifetime.\n\nA concurrent close() on the linked stream\u0027s fd triggers\nsnd_pcm_release_substream() \u2192 snd_pcm_drop() \u2192 pcm_release_private()\n\u2192 snd_pcm_unlink() \u2192 snd_pcm_detach_substream() \u2192 kfree(runtime).\nNo synchronization prevents kfree(runtime) from completing while the\ndrain path dereferences the stale pointer.\n\nFix by caching the needed runtime fields (no_period_wakeup, rate,\nbuffer_size) into local variables while still holding the stream lock,\nand using the cached values after the lock is released.",
"id": "GHSA-5cw4-rfp6-xjfx",
"modified": "2026-09-02T15:33:56Z",
"published": "2026-05-08T15:31:28Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-43437"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4a758e9a1f5ed722f83c4dd35f867fe811553bcb"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/629cf09464cf98670996ea5c191dc9743e6f3f00"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9b1dbd69ba6f8f8c69bc7b77c2ce3b9c6ed05ba6"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9baee36e8c5443411c4629afabafaff8a46a23fd"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ae8f8d30d334bad5b1b3cdb1eb8a0b771f55e432"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c2f64e05a0587a83ec42dbd6b7a7ded79b2ff694"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f2cb2e0d27fb925c73a78f0ce7d6dbf68d3747c1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/fc71f888994569f87d5bee20b1ac6c9c1e3a7a79"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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