CVE-2026-74261
In the Linux kernel, the following vulnerability has been resolved:
ALSA: seq: avoid stale FIFO cells during resize
snd_seq_fifo_resize() still needs to publish the replacement pool before it waits for FIFO users. A blocking snd_seq_read() holds f->use_lock while it sleeps, so concurrent senders must be able to queue to the new pool and wake that reader instead of failing against a closing old pool.
However, snd_seq_fifo_event_in() duplicates an event before it takes f->lock, and snd_seq_read() can dequeue a cell and later call snd_seq_fifo_cell_putback() if copy_to_user() or snd_seq_expand_var_event() fails.
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If resize swaps f->pool and detaches oldhead in between, either path can relink an old-pool cell after the snapshot. That stale cell sits outside the drained oldhead list, keeps oldpool->counter elevated, and can leave snd_seq_pool_delete() waiting for the retired pool to drain.
Keep the existing swap-before-wait ordering in snd_seq_fifo_resize(), but reject stale cells before any FIFO relink. Revalidate event-in cells under f->lock and retry them against the published replacement pool, and free stale putback cells instead of linking them back into the FIFO.
The buggy scenario involves two paths, with each column showing the order within that path:
resize path: relink path: 1. Allocate newpool. 1. Take f->use_lock. 2. Swap f->pool to newpool and 2. Duplicate or dequeue an old-pool detach oldhead. cell before oldpool closes. 3. Mark oldpool closing and 3. Reach a later relink point after wait for FIFO users. resize published newpool. 4. Free oldhead and delete 4. Relink the old-pool cell after oldpool. resize detached oldhead. 5. Drop f->use_lock.
The reproducer reports a resize ioctl blocked in the expected pool teardown path:
A second run with larger pools hit the same target path:
Detalles técnicos trazas, registros y código del informe original
signal: resize iteration=98 target_pool=4 exceeded 250ms
(elapsed=251ms)
diagnostic: resize_tid=651 wchan=snd_seq_pool_done
diagnostic: resize_tid=651 stack=
snd_seq_pool_done+0x5b/0x140
snd_seq_pool_delete+0x7a/0x90
snd_seq_fifo_resize+0x193/0x1e0
snd_seq_ioctl_set_client_pool+0x214/0x260
snd_seq_ioctl+0x119/0x540
__x64_sys_ioctl+0xd1/0x120
do_syscall_64+0xbb/0x2f0
entry_SYSCALL_64_after_hwframe+0x77/0x7f
signal: resize iteration=32 target_pool=64 exceeded 250ms
(elapsed=251ms)
diagnostic: resize_tid=663 wchan=snd_seq_pool_done
diagnostic: resize_tid=663 stack=
snd_seq_pool_done+0x5b/0x140
snd_seq_pool_delete+0x7a/0x90
snd_seq_fifo_resize+0x193/0x1e0
snd_seq_ioctl_set_client_pool+0x214/0x260
snd_seq_ioctl+0x119/0x540
__x64_sys_ioctl+0xd1/0x120
do_syscall_64+0xbb/0x2f0
entry_SYSCALL_64_after_hwframe+0x77/0x7fCVSS
NVD no ha asignado puntuación CVSS a esta CVE (habitual desde el cambio de política de abril de 2026).
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.21%
- Percentil entre todas las CVEs puntuadas: 10
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-74261",
"cveTags": [],
"metrics": {},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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{
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"programFiles": [
"sound/core/seq/seq_fifo.c"
],
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{
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],
"published": "2026-08-15T06:22:25.307",
"references": [
{
"url": "https://git.kernel.org/stable/c/1c4c35fb68d520241f7d9f1c356b5e2370fd8364",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: seq: avoid stale FIFO cells during resize\n\nsnd_seq_fifo_resize() still needs to publish the replacement pool\nbefore it waits for FIFO users. A blocking snd_seq_read() holds\nf->use_lock while it sleeps, so concurrent senders must be able to\nqueue to the new pool and wake that reader instead of failing against a\nclosing old pool.\n\nHowever, snd_seq_fifo_event_in() duplicates an event before it takes\nf->lock, and snd_seq_read() can dequeue a cell and later call\nsnd_seq_fifo_cell_putback() if copy_to_user() or\nsnd_seq_expand_var_event() fails. If resize swaps f->pool and detaches\noldhead in between, either path can relink an old-pool cell after the\nsnapshot. That stale cell sits outside the drained oldhead list, keeps\noldpool->counter elevated, and can leave snd_seq_pool_delete() waiting\nfor the retired pool to drain.\n\nKeep the existing swap-before-wait ordering in snd_seq_fifo_resize(),\nbut reject stale cells before any FIFO relink. Revalidate event-in cells\nunder f->lock and retry them against the published replacement pool, and\nfree stale putback cells instead of linking them back into the FIFO.\n\nThe buggy scenario involves two paths, with each column showing the\norder within that path:\n\nresize path: relink path:\n1. Allocate newpool. 1. Take f->use_lock.\n2. Swap f->pool to newpool and 2. Duplicate or dequeue an old-pool\n detach oldhead. cell before oldpool closes.\n3. Mark oldpool closing and 3. Reach a later relink point after\n wait for FIFO users. resize published newpool.\n4. Free oldhead and delete 4. Relink the old-pool cell after\n oldpool. resize detached oldhead.\n 5. Drop f->use_lock.\n\nThe reproducer reports a resize ioctl blocked in the expected pool\nteardown path:\n\nsignal: resize iteration=98 target_pool=4 exceeded 250ms\n (elapsed=251ms)\ndiagnostic: resize_tid=651 wchan=snd_seq_pool_done\ndiagnostic: resize_tid=651 stack=\n snd_seq_pool_done+0x5b/0x140\n snd_seq_pool_delete+0x7a/0x90\n snd_seq_fifo_resize+0x193/0x1e0\n snd_seq_ioctl_set_client_pool+0x214/0x260\n snd_seq_ioctl+0x119/0x540\n __x64_sys_ioctl+0xd1/0x120\n do_syscall_64+0xbb/0x2f0\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nA second run with larger pools hit the same target path:\n\nsignal: resize iteration=32 target_pool=64 exceeded 250ms\n (elapsed=251ms)\ndiagnostic: resize_tid=663 wchan=snd_seq_pool_done\ndiagnostic: resize_tid=663 stack=\n snd_seq_pool_done+0x5b/0x140\n snd_seq_pool_delete+0x7a/0x90\n snd_seq_fifo_resize+0x193/0x1e0\n snd_seq_ioctl_set_client_pool+0x214/0x260\n snd_seq_ioctl+0x119/0x540\n __x64_sys_ioctl+0xd1/0x120\n do_syscall_64+0xbb/0x2f0\n entry_SYSCALL_64_after_hwframe+0x77/0x7f"
}
],
"lastModified": "2026-08-17T06:19:19.603",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}