Linux Kernel XFS: Stale Data Mappings Post ILOCK Reacquire Causing DirectIO Race
CVE-2026-64600 Published on July 23, 2026
xfs: resample the data fork mapping after cycling ILOCK
In the Linux kernel, the following vulnerability has been resolved:
xfs: resample the data fork mapping after cycling ILOCK
xfs_reflink_fill_{cow_hole,delalloc} are both presented with an inode,
a data fork mapping, and a cow fork mapping. Unfortunately, these two
helpers cycle the ILOCK to grab a transaction, which means that the
mappings are stale as soon as we reacquire the ILOCK. Currently we
refresh the cow fork mapping by re-calling xfs_find_trim_cow_extent, but
we don't refresh the data fork mapping beforehand, which means that the
xfs_bmap_trim_cow in that function queries the refcount btree about the
wrong physical blocks and returns an inaccurate value in *shared.
If *shared is now false, the directio write proceeds with a stale data
fork mapping. Fix this by querying the data fork mapping if the
sequence counter changes across the ILOCK cycle.
Products Associated with CVE-2026-64600
stack.watch emails you whenever new vulnerabilities are published in Linux Kernel or Canonical Ubuntu Linux. Just hit a watch button to start following.
Affected Versions
Linux:- Version 3c68d44a2b49a0ac9165faa9c191e1e618c8a8d5 and below dc11be133efca5fe3a2fb02b016dee825cc12f18 is affected.
- Version 3c68d44a2b49a0ac9165faa9c191e1e618c8a8d5 and below b8c9aa832b52680ee40d6cab0efb081f9a69df05 is affected.
- Version 3c68d44a2b49a0ac9165faa9c191e1e618c8a8d5 and below 50f0012da1040f69a4e788cd9aed587c9a04983f is affected.
- Version 3c68d44a2b49a0ac9165faa9c191e1e618c8a8d5 and below e705d81a7193dd19e69b8e2bad4696d78a4ea075 is affected.
- Version 3c68d44a2b49a0ac9165faa9c191e1e618c8a8d5 and below 206c09b04dc5469c7ff14d8aceff2d47c88078d9 is affected.
- Version 3c68d44a2b49a0ac9165faa9c191e1e618c8a8d5 and below 44f891bc088958399eec27f7604928694aa35581 is affected.
- Version 3c68d44a2b49a0ac9165faa9c191e1e618c8a8d5 and below 2f4acd0fcd862e22eab45690ec2c08c80b6ef2e7 is affected.
- Version 4.11 is affected.
- Before 4.11 is unaffected.
- Version 5.15.212, <= 5.15.* is unaffected.
- Version 6.1.178, <= 6.1.* is unaffected.
- Version 6.6.145, <= 6.6.* is unaffected.
- Version 6.12.96, <= 6.12.* is unaffected.
- Version 6.18.39, <= 6.18.* is unaffected.
- Version 7.1.4, <= 7.1.* is unaffected.
- Version 7.2, <= * is unaffected.