CVE-2026-74601 (GCVE-0-2026-74601)
Vulnerability from cvelistv5
Published
2026-08-22 15:31
Modified
2026-08-25 05:40
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
ring-buffer: Use current_context for safe per-CPU buffer swap
The ring_buffer_swap_cpu() function currently checks the per-CPU
committing counter to determine if a buffer is actively being written to
before performing the swap. However, there exists a race window where
this check can be bypassed:
ring_buffer_lock_reserve
cpu_buffer = buffer->buffers[cpu]; // cpu_buffer_a
rb_reserve_next_event
rb_start_commit // inc committing
if (unlikely(READ_ONCE(cpu_buffer->buffer) != buffer)) {...}
__rb_reserve_next
rb_move_tail
rb_end_commit(cpu_buffer); // dec committing => 0
/* interrupt hits here, successfully swaps! */
local_inc(&cpu_buffer->committing);
ring_buffer_unlock_commit
cpu_buffer = buffer->buffers[cpu]; // cpu_buffer_b
rb_commit
rb_end_commit
RB_WARN_ON(cpu_buffer, !local_read(&cpu_buffer->committing))
// triggers warning
The committing counter can temporarily drop to 0 during a single write
operation (within rb_move_tail), creating a window where swap can
succeed even though the write is still in progress. This leads to
inconsistent buffer state and triggers the RB_WARN_ON in rb_commit().
Replace the committing counter check with current_context checks, which
are set at the entry of ring_buffer_lock_reserve() and remain valid
throughout the entire write operation, providing a reliable indicator of
buffer busy state during swap.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 4239c38fe0b3847e1e6d962c74b41b08ba0e2990 Version: 4239c38fe0b3847e1e6d962c74b41b08ba0e2990 Version: 4239c38fe0b3847e1e6d962c74b41b08ba0e2990 Version: 4239c38fe0b3847e1e6d962c74b41b08ba0e2990 Version: 4239c38fe0b3847e1e6d962c74b41b08ba0e2990 Version: 4239c38fe0b3847e1e6d962c74b41b08ba0e2990 Version: 4239c38fe0b3847e1e6d962c74b41b08ba0e2990 Version: 4239c38fe0b3847e1e6d962c74b41b08ba0e2990 |
||
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"kernel/trace/ring_buffer.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
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"vendor": "Linux",
"versions": [
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"status": "affected",
"version": "4.5"
},
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"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.266",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.217",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.184",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "6.6.153",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.105",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.45",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.9",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
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"vulnerable": true
},
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{
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}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nring-buffer: Use current_context for safe per-CPU buffer swap\n\nThe ring_buffer_swap_cpu() function currently checks the per-CPU\ncommitting counter to determine if a buffer is actively being written to\nbefore performing the swap. However, there exists a race window where\nthis check can be bypassed:\n\n ring_buffer_lock_reserve\n cpu_buffer = buffer-\u003ebuffers[cpu]; // cpu_buffer_a\n rb_reserve_next_event\n rb_start_commit // inc committing\n if (unlikely(READ_ONCE(cpu_buffer-\u003ebuffer) != buffer)) {...}\n __rb_reserve_next\n rb_move_tail\n rb_end_commit(cpu_buffer); // dec committing =\u003e 0\n /* interrupt hits here, successfully swaps! */\n local_inc(\u0026cpu_buffer-\u003ecommitting);\n\n ring_buffer_unlock_commit\n cpu_buffer = buffer-\u003ebuffers[cpu]; // cpu_buffer_b\n rb_commit\n rb_end_commit\n RB_WARN_ON(cpu_buffer, !local_read(\u0026cpu_buffer-\u003ecommitting))\n // triggers warning\n\nThe committing counter can temporarily drop to 0 during a single write\noperation (within rb_move_tail), creating a window where swap can\nsucceed even though the write is still in progress. This leads to\ninconsistent buffer state and triggers the RB_WARN_ON in rb_commit().\n\nReplace the committing counter check with current_context checks, which\nare set at the entry of ring_buffer_lock_reserve() and remain valid\nthroughout the entire write operation, providing a reliable indicator of\nbuffer busy state during swap."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - Exploitation requires local tracefs writes to snapshot or latency tracers; ring_buffer_swap_cpu() is only reached from update_max_tr_single() via tracing_snapshot_write or irqsoff/preemptoff tracers, with no network, adjacent, or physical entry path.\nAC:L - The attacker controls both sides of the race by enabling irqsoff/preemptoff tracing or hammering per_cpu/*/snapshot while generating trace events that cross page boundaries, reliably hitting the rb_move_tail window where committing briefly drops to zero.\nPR:L - tracing_check_open_get_tr() enforces only LOCKDOWN_TRACEFS and DAC with no capable() check; tracefs gid= mounts, Android/Perfetto/ChromeOS tracing groups, and container user+mount namespaces routinely grant unprivileged local write access to snapshot and current_tracer.\nUI:N - The attacker enables tracers and triggers buffer swaps through their own tracefs writes and syscalls; no victim cooperation, unrelated user action, or third-party interaction is required.\nS:U - Impact is corrupted kernel ring-buffer metadata and WARN_ON within the same kernel security domain; this is not a VM escape, IOMMU bypass, or cross-authority sandbox breakout.\nC:H - Swapping per-CPU buffers mid-write leaves ring_buffer_per_cpu page, tail, and commit state inconsistent across buffers; subsequent trace reads or commits can access wrong backing pages, constituting kernel-memory corruption with arbitrary-read potential.\nI:H - Mid-reservation buffer swap causes unlock_commit on the wrong cpu_buffer with mismatched tail/commit page pointers, corrupting ring-buffer page lists and write metadata in ways exploitable for heap corruption and control-flow manipulation.\nA:H - rb_end_commit() hits RB_WARN_ON triggering WARN_ON and disabling recording; corrupted ring-buffer page state from this swap race has caused kernel oops/panic in related ring_buffer_swap_cpu bugs, and panic_on_warn makes the WARN fatal."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-25T05:40:26.170Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/26662bc8fced1d668fa1aa146eda085bfc67bd0b"
},
{
"url": "https://git.kernel.org/stable/c/6b524e6b234e45c7f5f90d13b042c6f57f80105c"
},
{
"url": "https://git.kernel.org/stable/c/597f279b7b4a06412e3d965e98cc36e181cdbede"
},
{
"url": "https://git.kernel.org/stable/c/22709117d9ae95e52673685f98caac7c356a8227"
},
{
"url": "https://git.kernel.org/stable/c/ad7e10c7ea89af45ac1bf1814855d45da472703d"
},
{
"url": "https://git.kernel.org/stable/c/5b926fb04cb9ef3156dcf88c69a59d3d1a1c4f9f"
},
{
"url": "https://git.kernel.org/stable/c/5e6e2a18c20e88167d414f666032792e8bf19b80"
},
{
"url": "https://git.kernel.org/stable/c/f27bdc43077e4fcb5557dfc315ee8d91e741f483"
}
],
"title": "ring-buffer: Use current_context for safe per-CPU buffer swap",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74601",
"datePublished": "2026-08-22T15:31:50.092Z",
"dateReserved": "2026-08-15T05:44:03.919Z",
"dateUpdated": "2026-08-25T05:40:26.170Z",
"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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