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CVE PROGRAM SOURCE RECORD9.1 Critical

CVE-2026-89713

NFSD: check truncate permission under inode lock

Read JSON ↗CVE.org ↗
Status
Published
Published
Updated
Assigning organization
Linux

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.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • 783112f7401ff449d979530209b3f6c2594fdb4e to < 0669861a2e8e2bdb9c1149417d8ad821996ae4feaffected
  • 783112f7401ff449d979530209b3f6c2594fdb4e to < 52d0c5bdfe232c9974d4b11f97078b9c7814f05daffected
  • 783112f7401ff449d979530209b3f6c2594fdb4e to < 3afa17d93ba8c925f49370c816c6dae5112d8c24affected
  • 783112f7401ff449d979530209b3f6c2594fdb4e to < d8352da196349182e1afd5a93308256cddc0a97daffected
  • 783112f7401ff449d979530209b3f6c2594fdb4e to < 44086254479035de42ca3d286ecf25521d4e6325affected
  • 783112f7401ff449d979530209b3f6c2594fdb4e to < b778e0e0a16759f22a70579c3cf8d254a40d4a7faffected
  • 604a3c407026d6162d15300478e63f901e435efcaffected
  • cc4d5dc73841b98d33cdfb9822d70b0aac4beca5affected
  • 3ee4f442e5b37a537297b812557b1163f96b5399affected
  • a3c6cbc4eac4473ed5461d5faae2794d3e5c0e44affected
  • 982898d7f97a35447403c3fcecc0d96c646ce101affected
  • 3.2.89 to < 3.3affected
  • 3.16.44 to < 3.17affected
  • 4.4.53 to < 4.5affected
  • 4.9.14 to < 4.10affected
  • 4.10.2 to < 4.11affected

Linux Linux

Default version status: affected

  • 4.11affected
  • 0 to < 4.11unaffected
  • 6.1.191 to ≤ 6.1.*unaffected
  • 6.6.160 to ≤ 6.6.*unaffected
  • 6.12.109 to ≤ 6.12.*unaffected
  • 6.18.50 to ≤ 6.18.*unaffected
  • 7.2.4 to ≤ 7.2.*unaffected
  • 7.3 to ≤ *unaffected

References