xfs: fix freemap adjustments when adding xattrs to leaf blocks

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Summary

CVECVE-2026-43158
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-06 12:16:33 UTC
Updated2026-05-08 13:16:41 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: xfs: fix freemap adjustments when adding xattrs to leaf blocks xfs/592 and xfs/794 both trip this assertion in the leaf block freemap adjustment code after ~20 minutes of running on my test VMs: ASSERT(ichdr->firstused >= ichdr->count * sizeof(xfs_attr_leaf_entry_t) + xfs_attr3_leaf_hdr_size(leaf)); Upon enabling quite a lot more debugging code, I narrowed this down to fsstress trying to set a local extended attribute with namelen=3 and valuelen=71. This results in an entry size of 80 bytes. At the start of xfs_attr3_leaf_add_work, the freemap looks like this: i 0 base 448 size 0 rhs 448 count 46 i 1 base 388 size 132 rhs 448 count 46 i 2 base 2120 size 4 rhs 448 count 46 firstused = 520 where "rhs" is the first byte past the end of the leaf entry array. This is inconsistent -- the entries array ends at byte 448, but freemap[1] says there's free space starting at byte 388! By the end of the function, the freemap is in worse shape: i 0 base 456 size 0 rhs 456 count 47 i 1 base 388 size 52 rhs 456 count 47 i 2 base 2120 size 4 rhs 456 count 47 firstused = 440 Important note: 388 is not aligned with the entries array element size of 8 bytes. Based on the incorrect freemap, the name area starts at byte 440, which is below the end of the entries array! That's why the assertion triggers and the filesystem shuts down. How did we end up here? First, recall from the previous patch that the freemap array in an xattr leaf block is not intended to be a comprehensive map of all free space in the leaf block. In other words, it's perfectly legal to have a leaf block with: * 376 bytes in use by the entries array * freemap[0] has [base = 376, size = 8] * freemap[1] has [base = 388, size = 1500] * the space between 376 and 388 is free, but the freemap stopped tracking that some time ago If we add one xattr, the entries array grows to 384 bytes, and freemap[0] becomes [base = 384, size = 0]. So far, so good. But if we add a second xattr, the entries array grows to 392 bytes, and freemap[0] gets pushed up to [base = 392, size = 0]. This is bad, because freemap[1] hasn't been updated, and now the entries array and the free space claim the same space. The fix here is to adjust all freemap entries so that none of them collide with the entries array. Note that this fix relies on commit 2a2b5932db6758 ("xfs: fix attr leaf header freemap.size underflow") and the previous patch that resets zero length freemap entries to have base = 0.

Risk And Classification

Primary CVSS: v3.1 8.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.000530000 probability, percentile 0.164320000 (date 2026-05-11)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary8.8HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED8.8HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 d08976725355b9d54d8332fce223fa281cc304a5 git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 6a8737afbccc340e718e0b22577312826390be8b git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 a396b3d73d51355e50acdb403ba9c4cae4c1174e git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 38613c01f69e1e77e6b8acab1e8ac665d01c2f15 git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 ef42a8766ff3fdf51cf72fb36d0859c09d134478 git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 43f3b18679615a93bd848afde3602ba160637a46 git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 24ce71852f2cee6581e2cbebc15489ed52bf63b7 git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 3eefc0c2b78444b64feeb3783c017d6adc3cd3ce 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/ef42a8766ff3fdf51cf72fb36d0859c09d134478 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/24ce71852f2cee6581e2cbebc15489ed52bf63b7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d08976725355b9d54d8332fce223fa281cc304a5 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/43f3b18679615a93bd848afde3602ba160637a46 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/6a8737afbccc340e718e0b22577312826390be8b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/3eefc0c2b78444b64feeb3783c017d6adc3cd3ce 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/38613c01f69e1e77e6b8acab1e8ac665d01c2f15 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a396b3d73d51355e50acdb403ba9c4cae4c1174e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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