mm/damon/sysfs-schemes: protect memcg_path kfree() with damon_sysfs_lock

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Summary

CVECVE-2026-46121
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-28 10:16:27 UTC
Updated2026-05-28 13:44:01 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: mm/damon/sysfs-schemes: protect memcg_path kfree() with damon_sysfs_lock Patch series "mm/damon/sysfs-schemes: fix use-after-free for [memcg_]path". Reads of 'memcg_path' and 'path' files in DAMON sysfs interface could race with their writes, results in use-after-free. Fix those. This patch (of 2): damon_sysfs_scheme_filter->mmecg_path can be read and written by users, via DAMON sysfs memcg_path file. It can also be indirectly read, for the parameters {on,off}line committing to DAMON. The reads for parameters committing are protected by damon_sysfs_lock to avoid the sysfs files being destroyed while any of the parameters are being read. But the user-driven direct reads and writes are not protected by any lock, while the write is deallocating the memcg_path-pointing buffer. As a result, the readers could read the already freed buffer (user-after-free). Note that the user-reads don't race when the same open file is used by the writer, due to kernfs's open file locking. Nonetheless, doing the reads and writes with separate open files would be common. Fix it by protecting both the user-direct reads and writes with damon_sysfs_lock.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 490a43d07f1663d827e802720d30cbc0494e4f81 b1e9f2d5870776347edef927f9bb3ea19b8e3abb git Not specified
CNA Linux Linux affected c5d5b0047b0c0f304608f3824139f7bd34c48413 c88802d0e8edd14b6cd2daf3000f99adbc4c85c5 git Not specified
CNA Linux Linux affected 4f489fe6afb395dbc79840efa3c05440b760d883 eafd6f5372d29b0dd213799b92c2c9c7ad31d7da git Not specified
CNA Linux Linux affected 4f489fe6afb395dbc79840efa3c05440b760d883 baecc45ad60e621ef14d6c1e7f41ef36bbfdf910 git Not specified
CNA Linux Linux affected 4f489fe6afb395dbc79840efa3c05440b760d883 1e68eb96e8beb1abefd12dd22c5637795d8a877e git Not specified
CNA Linux Linux affected 4a158ac0538dd5695eeaa00aa0720d711f3e4ef1 git Not specified
CNA Linux Linux affected 6.6.96 6.6.140 semver Not specified
CNA Linux Linux affected 6.12.36 6.12.88 semver Not specified
CNA Linux Linux affected 6.15.5 6.16 semver Not specified
CNA Linux Linux affected 6.16 Not specified
CNA Linux Linux unaffected 6.16 semver Not specified
CNA Linux Linux unaffected 6.6.140 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.88 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.30 6.18.* semver Not specified
CNA Linux Linux unaffected 7.0.7 7.0.* semver Not specified
CNA Linux Linux unaffected 7.1-rc2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/c88802d0e8edd14b6cd2daf3000f99adbc4c85c5 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b1e9f2d5870776347edef927f9bb3ea19b8e3abb 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/1e68eb96e8beb1abefd12dd22c5637795d8a877e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/baecc45ad60e621ef14d6c1e7f41ef36bbfdf910 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/eafd6f5372d29b0dd213799b92c2c9c7ad31d7da 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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