DescriptionIn the Linux kernel, the following vulnerability has been resolved: mm: cachestat: fix folio read-after-free in cache walk In cachestat, we access the folio from the page cache's xarray to compute its page offset, and check for its dirty and writeback flags. However, we do not hold a reference to the folio before performing these actions, which means the folio can concurrently be released and reused as another folio/page/slab. Get around this altogether by just using xarray's existing machinery for the folio page offsets and dirty/writeback states. This changes behavior for tmpfs files to now always report zeroes in their dirty and writeback counters. This is okay as tmpfs doesn't follow conventional writeback cache behavior: its pages get "cleaned" during swapout, after which they're no longer resident etc.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
linux (PTS)bullseye5.10.218-1fixed
bullseye (security)5.10.221-1fixed
bookworm (security)6.1.90-1fixed

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

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
linuxsourcebuster(not affected)
linuxsourcebullseye(not affected)
linuxsourcebookworm(not affected)


[bookworm] - linux <not-affected> (Vulnerable code not present)
[bullseye] - linux <not-affected> (Vulnerable code not present)
[buster] - linux <not-affected> (Vulnerable code not present) (6.8-rc7)

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