xfs: delete attr leaf freemap entries when empty

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Summary

CVECVE-2026-43187
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-06 12:16:37 UTC
Updated2026-05-06 13:07:51 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: xfs: delete attr leaf freemap entries when empty Back in commit 2a2b5932db6758 ("xfs: fix attr leaf header freemap.size underflow"), Brian Foster observed that it's possible for a small freemap at the end of the end of the xattr entries array to experience a size underflow when subtracting the space consumed by an expansion of the entries array. There are only three freemap entries, which means that it is not a complete index of all free space in the leaf block. This code can leave behind a zero-length freemap entry with a nonzero base. Subsequent setxattr operations can increase the base up to the point that it overlaps with another freemap entry. This isn't in and of itself a problem because the code in _leaf_add that finds free space ignores any freemap entry with zero size. However, there's another bug in the freemap update code in _leaf_add, which is that it fails to update a freemap entry that begins midway through the xattr entry that was just appended to the array. That can result in the freemap containing two entries with the same base but different sizes (0 for the "pushed-up" entry, nonzero for the entry that's actually tracking free space). A subsequent _leaf_add can then allocate xattr namevalue entries on top of the entries array, leading to data loss. But fixing that is for later. For now, eliminate the possibility of confusion by zeroing out the base of any freemap entry that has zero size. Because the freemap is not intended to be a complete index of free space, a subsequent failure to find any free space for a new xattr will trigger block compaction, which regenerates the freemap. It looks like this bug has been in the codebase for quite a long time.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 f3c0d1fc1eadbb4adbee5ab7757d41d35f48325b git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 aa9083d97e2157da3c6fb45ddb1a97af7f188f7f git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 a631899025d47ea1aa6464d76db5b4d3b6d196fd git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 ffaf5c99d0f862db021fb1af8b813c1416b1beb2 git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 e1b8c6452ee99a30e188a88f3f3f804fb1c6004a git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 f31a8334e1c54b126fcecf98645a49b6bc5ad399 git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 479b05fc3ee272090f671b06a41f3da8aa78eece git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 6f13c1d2a6271c2e73226864a0e83de2770b6f34 git Not specified
CNA Linux Linux affected 2.6.12 Not specified
CNA Linux Linux unaffected 2.6.12 semver Not specified
CNA Linux Linux unaffected 5.10.252 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.202 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.165 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.128 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.75 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.16 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19.6 6.19.* semver Not specified
CNA Linux Linux unaffected 7.0 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/a631899025d47ea1aa6464d76db5b4d3b6d196fd 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f31a8334e1c54b126fcecf98645a49b6bc5ad399 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/e1b8c6452ee99a30e188a88f3f3f804fb1c6004a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/aa9083d97e2157da3c6fb45ddb1a97af7f188f7f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/479b05fc3ee272090f671b06a41f3da8aa78eece 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f3c0d1fc1eadbb4adbee5ab7757d41d35f48325b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/ffaf5c99d0f862db021fb1af8b813c1416b1beb2 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/6f13c1d2a6271c2e73226864a0e83de2770b6f34 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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