FKIE_CVE-2026-89644
Vulnerability from fkie_nvd - Published: 2026-09-11 20:19 - Updated: 2026-09-11 20:19
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved:
btrfs: fix extent map leak in NOCOW direct I/O write
btrfs_dio_iomap_begin() calls btrfs_get_extent(), which returns an
extent map reference that must be dropped on all exit paths.
For direct writes into a NOCOW range, btrfs_get_blocks_direct_write()
keeps using that extent map and asks btrfs_create_dio_extent() to
allocate the ordered extent. If that fails, for example because
btrfs_alloc_ordered_extent() fails, the function returns the error
without dropping the input extent map. The PREALLOC path avoided this by
dropping the input extent map before replacing it with the newly created
one.
Check the error from btrfs_create_dio_extent() before replacing the
map and drop the input extent map on failure.
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/btrfs/direct-io.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "f42efd634c0ae7ba0ce2fc5e30e291b0803b0ae2",
"status": "affected",
"version": "5f9a8a51d8b95505d8de8b7191ae2ed8c504d4af",
"versionType": "git"
},
{
"lessThan": "05a1a816eef8b3e4332620a64fc8cf45c4eb5c0d",
"status": "affected",
"version": "5f9a8a51d8b95505d8de8b7191ae2ed8c504d4af",
"versionType": "git"
},
{
"lessThan": "3f950867c307c5413d628a153ac44915bd117ffd",
"status": "affected",
"version": "5f9a8a51d8b95505d8de8b7191ae2ed8c504d4af",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"fs/btrfs/direct-io.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "4.7"
},
{
"lessThan": "4.7",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.50",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.2.*",
"status": "unaffected",
"version": "7.2.4",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.3-rc1",
"versionType": "original_commit_for_fix"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix extent map leak in NOCOW direct I/O write\n\nbtrfs_dio_iomap_begin() calls btrfs_get_extent(), which returns an\nextent map reference that must be dropped on all exit paths.\n\nFor direct writes into a NOCOW range, btrfs_get_blocks_direct_write()\nkeeps using that extent map and asks btrfs_create_dio_extent() to\nallocate the ordered extent. If that fails, for example because\nbtrfs_alloc_ordered_extent() fails, the function returns the error\nwithout dropping the input extent map. The PREALLOC path avoided this by\ndropping the input extent map before replacing it with the newly created\none.\n\nCheck the error from btrfs_create_dio_extent() before replacing the\nmap and drop the input extent map on failure."
}
],
"id": "CVE-2026-89644",
"lastModified": "2026-09-11T20:19:50.223",
"metrics": {},
"published": "2026-09-11T20:19:50.223",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/05a1a816eef8b3e4332620a64fc8cf45c4eb5c0d"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/3f950867c307c5413d628a153ac44915bd117ffd"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/f42efd634c0ae7ba0ce2fc5e30e291b0803b0ae2"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Received"
}
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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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