CVE-2026-64600

NameCVE-2026-64600
DescriptionIn 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.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
ReferencesDLA-4720-1, DLA-4723-1, DLA-4724-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
linux (PTS)bullseye5.10.223-1vulnerable
bullseye (security)5.10.262-1vulnerable
bookworm6.1.176-1vulnerable
bookworm (security)6.1.180-1fixed
trixie6.12.94-1vulnerable
trixie (security)6.12.101-1fixed
forky7.1.7-1fixed
sid7.1.8-1fixed
linux-6.1 (PTS)bullseye (security)6.1.180-1~deb11u1fixed
linux-6.12 (PTS)bookworm (security)6.12.100-1~deb12u1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
linuxsourcebookworm6.1.180-1DLA-4720-1
linuxsourcetrixie6.12.96-1
linuxsource(unstable)7.1.4-1
linux-6.1sourcebullseye6.1.180-1~deb11u1DLA-4723-1
linux-6.12sourcebookworm6.12.100-1~deb12u1DLA-4724-1

Notes

https://www.openwall.com/lists/oss-security/2026/07/22/14
https://git.kernel.org/linus/2f4acd0fcd862e22eab45690ec2c08c80b6ef2e7 (7.2-rc4)

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