CVE-2026-74261 (GCVE-0-2026-74261)
Vulnerability from cvelistv5
Published
2026-08-15 05:57
Modified
2026-08-17 05:16
Severity ?
VLAI Severity ?
EPSS score ?
Summary
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. 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:
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
A second run with larger pools hit the same target path:
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+0x77/0x7f
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 2d7d54002e396c180db0c800c1046f0a3c471597 Version: 2d7d54002e396c180db0c800c1046f0a3c471597 Version: 2d7d54002e396c180db0c800c1046f0a3c471597 Version: df7a2d0af9f7ab73cf22a7b62bbc0bad93a02110 Version: 28e0ebdd57cd3287ac821068364b74c70af3861c Version: d4b8e8a32d74052fe292618ae19f794944ddc673 Version: e91325f27c4d98d1088e9e86b3ab475f752eeb80 Version: 9ebfed203c0d93449a074c5c2fd5bb3e58518f0d Version: 3492352e1f34673708fa7409b4b1d97545aa2f1c Version: a90d7447e4a154ad26e3b9e09a0878680be49339 Version: 74a2c1ff88a4e0960623d17f7db56ac5a60bb0cf Version: c36ef6467420f8982e6d4d6f93d0634a85a5ee45 Version: 3.2.91 ≤ Version: 3.10.107 ≤ Version: 3.12.73 ≤ Version: 3.16.46 ≤ Version: 3.18.50 ≤ Version: 4.1.40 ≤ Version: 4.4.60 ≤ Version: 4.9.21 ≤ Version: 4.10.9 ≤ |
||
{
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"cpeApplicability": [
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],
"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-\u003euse_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-\u003elock, 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-\u003epool 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-\u003ecounter 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-\u003elock 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-\u003euse_lock.\n2. Swap f-\u003epool 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-\u003euse_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"
}
],
"providerMetadata": {
"dateUpdated": "2026-08-17T05:16:03.389Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/98a965cb1e767b54b6bbd831b6cea26f521a8f51"
},
{
"url": "https://git.kernel.org/stable/c/1c4c35fb68d520241f7d9f1c356b5e2370fd8364"
},
{
"url": "https://git.kernel.org/stable/c/e546128291f8d688dcb931827e2efd2aa6c0734d"
}
],
"title": "ALSA: seq: avoid stale FIFO cells during resize",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74261",
"datePublished": "2026-08-15T05:57:38.311Z",
"dateReserved": "2026-08-15T05:44:03.877Z",
"dateUpdated": "2026-08-17T05:16:03.389Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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