In 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.
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.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
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| Linux | Linux | affected |
|
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Fixes
Solution
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Workaround
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References
History
Thu, 07 May 2026 04:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-119 CWE-665 |
Thu, 07 May 2026 00:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-131 | |
| References |
| |
| Metrics |
threat_severity
|
cvssV3_1
|
Wed, 06 May 2026 18:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-119 CWE-665 |
Wed, 06 May 2026 12:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In 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. | |
| Title | xfs: fix freemap adjustments when adding xattrs to leaf blocks | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-05-06T11:27:37.848Z
Reserved: 2026-05-01T14:12:55.990Z
Link: CVE-2026-43158
Vulnrichment
No data.
NVD
Status : Awaiting Analysis
Published: 2026-05-06T12:16:33.697
Modified: 2026-05-06T13:07:51.607
Link: CVE-2026-43158
Redhat
OpenCVE Enrichment
Updated: 2026-05-07T04:30:21Z
Weaknesses