CVE-2026-74591 (GCVE-0-2026-74591)
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:
mm/filemap: __filemap_add_folio() restore index before retrying
In __filemap_add_folio()'s split-a-conflict loop, xas_set_order() is
applied repeatedly: each application modifies xas.xa_index, rounding it
down according to the split_order attempted at that stage: and if all goes
as intended, it eventually (or immediately) converges on an
xas_try_split() to the required folio_order, with xas.xa_index now the
same as index: then xas_store() puts the new folio into the xarray there.
But if a new node was needed, and GFP_NOWAIT allocation did not get one,
the lock is dropped, xas_nomem() used to allocate, and sequence retried.
If (that part of) the xarray is unchanged when the lock is reacquired, no
problem. But what if the conflict was meanwhile resolved by another
thread (perhaps even doing the same thing, inserting a folio at that same
index)? Isn't there a danger of now putting our folio into the xarray at
an intermediate rounded-down index? With !folio_contains() bug to follow,
when CONFIG_DEBUG_VM=y is checking for that.
Fix this with an xas_set_order() to restore the original xas.xa_index at
the bottom of the loop, so the retry does a full re-evaluation after
reacquiring the lock, and cannot reach xas_store() with the wrong index.
Production was suffering from rare SIGILLs and SIGSEGVs, executable text
found a page away from where it belonged, !folio_contains() bug hit when
debug enabled: symptoms not seen since this patch went in.
References
Impacted products
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"mm/filemap.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "4917e3ebcab50f0265e8ca01c8567de4c4a47511",
"status": "affected",
"version": "200a89c159a7a416115e6e309183c82183bf98aa",
"versionType": "git"
},
{
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"status": "affected",
"version": "200a89c159a7a416115e6e309183c82183bf98aa",
"versionType": "git"
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"status": "affected",
"version": "200a89c159a7a416115e6e309183c82183bf98aa",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"mm/filemap.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.15"
},
{
"lessThan": "6.15",
"status": "unaffected",
"version": "0",
"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": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.45",
"versionStartIncluding": "6.15",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.1.9",
"versionStartIncluding": "6.15",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/filemap: __filemap_add_folio() restore index before retrying\n\nIn __filemap_add_folio()\u0027s split-a-conflict loop, xas_set_order() is\napplied repeatedly: each application modifies xas.xa_index, rounding it\ndown according to the split_order attempted at that stage: and if all goes\nas intended, it eventually (or immediately) converges on an\nxas_try_split() to the required folio_order, with xas.xa_index now the\nsame as index: then xas_store() puts the new folio into the xarray there.\n\nBut if a new node was needed, and GFP_NOWAIT allocation did not get one,\nthe lock is dropped, xas_nomem() used to allocate, and sequence retried. \nIf (that part of) the xarray is unchanged when the lock is reacquired, no\nproblem. But what if the conflict was meanwhile resolved by another\nthread (perhaps even doing the same thing, inserting a folio at that same\nindex)? Isn\u0027t there a danger of now putting our folio into the xarray at\nan intermediate rounded-down index? With !folio_contains() bug to follow,\nwhen CONFIG_DEBUG_VM=y is checking for that.\n\nFix this with an xas_set_order() to restore the original xas.xa_index at\nthe bottom of the loop, so the retry does a full re-evaluation after\nreacquiring the lock, and cannot reach xas_store() with the wrong index.\n\nProduction was suffering from rare SIGILLs and SIGSEGVs, executable text\nfound a page away from where it belonged, !folio_contains() bug hit when\ndebug enabled: symptoms not seen since this patch went in."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 9.8,
"baseSeverity": "CRITICAL",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - __filemap_add_folio() is reached from every page-cache insert path including nfsd vfs_iocb_iter_read() and ksmbd kernel_read() on internet-facing file servers, as well as local buffered reads, writes, and mmap faults via filemap_get_folio().\nAC:L - An attacker controls both sides of the race by issuing concurrent reads/writes or NFS/SMB requests to the same file offsets while applying memory pressure to force xas_nomem() xa_node allocation retries after lock drops.\nPR:N - Exploitation requires only the ability to trigger concurrent page-cache population on accessible files via network NFS/SMB reads or local syscalls; no real root, CAP_SYS_ADMIN, or init-namespace privileges are needed.\nUI:N - The corrupt insert is triggered entirely by attacker-driven concurrent I/O and memory pressure; no victim click, mount, or other interactive action beyond normal automated file access is required.\nS:U - Corruption is confined to the kernel page cache and process address spaces on the same host; it does not cross a VM, container runtime, or IOMMU security boundary to a separate authority.\nC:H - Storing a folio at a rounded-down xarray index maps the wrong physical page to a file offset, enabling cross-page disclosure of file or kernel data; production saw executable text one page away from its correct location.\nI:H - Wrong-index folio insertion corrupts page-cache mappings and served executable content, providing a memory-corruption primitive that can alter code and data seen by userspace mappings and enable further exploitation.\nA:H - Production systems experienced rare SIGILL and SIGSEGV crashes from corrupted mappings, and CONFIG_DEBUG_VM builds hit !folio_contains() BUG checks, demonstrating reliable kernel and process termination."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-25T05:40:18.794Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/4917e3ebcab50f0265e8ca01c8567de4c4a47511"
},
{
"url": "https://git.kernel.org/stable/c/267ecd2eb7759c26f1a026eb0a5b231071534c9c"
},
{
"url": "https://git.kernel.org/stable/c/86da3f7e1e609e1e8bfbab198af68467c5a015a5"
}
],
"title": "mm/filemap: __filemap_add_folio() restore index before retrying",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74591",
"datePublished": "2026-08-22T15:31:42.661Z",
"dateReserved": "2026-08-15T05:44:03.918Z",
"dateUpdated": "2026-08-25T05:40:18.794Z",
"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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