NFSD: check truncate permission under inode lock
Summary
| CVE | CVE-2026-89713 |
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| State | PUBLISHED |
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| Assigner | Linux |
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| Source Priority | CVE Program / NVD first with legacy fallback |
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| Published | 2026-09-11 20:19:58 UTC |
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| Updated | 2026-09-11 20:19:58 UTC |
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| Description | In the Linux kernel, the following vulnerability has been resolved:
NFSD: check truncate permission under inode lock
nfsd_setattr() checks whether a size update needs NFSD_MAY_TRUNC
before it takes inode_lock(). The comparison uses the file size sampled
by that unlocked read, but the actual ATTR_SIZE update is applied later
under inode_lock() by notify_change().
This leaves a TOCTOU window for append-only files. If a client sends a
SETATTR that does not shrink the file at the time of the unlocked
sample, a concurrent append can extend the file before nfsd_setattr()
takes inode_lock(). notify_change() then applies a real truncation
without the NFSD_MAY_TRUNC check that rejects IS_APPEND(inode). The VFS
truncate syscall paths perform their own append-only checks before
calling notify_change(), so NFSD must make this decision against the
locked size it is about to change.
Split the write-count acquisition from the truncation permission check.
Keep get_write_access() before the locked setattr work, then recheck
whether the requested size is below i_size_read(inode) after inode_lock()
has been acquired and before notify_change(ATTR_SIZE). This also avoids
the plain unlocked inode->i_size load. |
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Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|
| CNA |
Linux |
Linux |
affected 783112f7401ff449d979530209b3f6c2594fdb4e 3afa17d93ba8c925f49370c816c6dae5112d8c24 git |
Not specified |
| CNA |
Linux |
Linux |
affected 783112f7401ff449d979530209b3f6c2594fdb4e d8352da196349182e1afd5a93308256cddc0a97d git |
Not specified |
| CNA |
Linux |
Linux |
affected 783112f7401ff449d979530209b3f6c2594fdb4e 44086254479035de42ca3d286ecf25521d4e6325 git |
Not specified |
| CNA |
Linux |
Linux |
affected 783112f7401ff449d979530209b3f6c2594fdb4e b778e0e0a16759f22a70579c3cf8d254a40d4a7f git |
Not specified |
| CNA |
Linux |
Linux |
affected 604a3c407026d6162d15300478e63f901e435efc git |
Not specified |
| CNA |
Linux |
Linux |
affected cc4d5dc73841b98d33cdfb9822d70b0aac4beca5 git |
Not specified |
| CNA |
Linux |
Linux |
affected 3ee4f442e5b37a537297b812557b1163f96b5399 git |
Not specified |
| CNA |
Linux |
Linux |
affected a3c6cbc4eac4473ed5461d5faae2794d3e5c0e44 git |
Not specified |
| CNA |
Linux |
Linux |
affected 982898d7f97a35447403c3fcecc0d96c646ce101 git |
Not specified |
| CNA |
Linux |
Linux |
affected 3.2.89 3.3 semver |
Not specified |
| CNA |
Linux |
Linux |
affected 3.16.44 3.17 semver |
Not specified |
| CNA |
Linux |
Linux |
affected 4.4.53 4.5 semver |
Not specified |
| CNA |
Linux |
Linux |
affected 4.9.14 4.10 semver |
Not specified |
| CNA |
Linux |
Linux |
affected 4.10.2 4.11 semver |
Not specified |
| CNA |
Linux |
Linux |
affected 4.11 |
Not specified |
| CNA |
Linux |
Linux |
unaffected 4.11 semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.12.109 6.12.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.18.50 6.18.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.2.4 7.2.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.3-rc1 * original_commit_for_fix |
Not specified |
References
| Reference | Source | Link | Tags |
|---|
| git.kernel.org/stable/c/b778e0e0a16759f22a70579c3cf8d254a40d4a7f |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/d8352da196349182e1afd5a93308256cddc0a97d |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/44086254479035de42ca3d286ecf25521d4e6325 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/3afa17d93ba8c925f49370c816c6dae5112d8c24 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| CVE Program record |
CVE.ORG |
www.cve.org |
canonical |
| NVD vulnerability detail |
NVD |
nvd.nist.gov |
canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.