ext4: stop retrying saturated xattr cache entries
Summary
| CVE | CVE-2026-80808 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-09-04 16:18:07 UTC |
| Updated | 2026-09-04 16:18:07 UTC |
| Description | In the Linux kernel, the following vulnerability has been resolved: ext4: stop retrying saturated xattr cache entries ext4_xattr_block_set() retries when a cache entry selected for reuse has a saturated reference count after taking the buffer lock. The retry returns to the mbcache lookup without making that entry ineligible, so it can select the same unusable entry indefinitely. A task spinning there can hold the parent directory's i_rwsem and leave concurrent rmdir callers blocked. Normally a reusable entry has a reference count below EXT4_XATTR_REFCOUNT_MAX because the count and MBE_REUSABLE_B are updated under the same buffer lock. A corrupted filesystem can violate that invariant. The syzbot reproducer reports allocator and xattr corruption before triggering this retry loop. Check the untrusted on-disk count before incrementing it, avoiding overflow, and clear MBE_REUSABLE_B when it is already saturated. The next lookup then skips the entry that was just proven unusable. This mirrors the normal transition at EXT4_XATTR_REFCOUNT_MAX; the release path marks the entry reusable again on the exact 1024-to-1023 transition. Using the same QEMU harness and guest parameters, current unpatched Linux hung in 6 of 8 420-second trials with the do_rmdir signature; representative NMI backtraces caught the owner spinning in ext4_xattr_block_set(). The patched kernel completed 28 of 28 trials without a hung-task report; the final twelve trials exercised the reviewed overflow-safe form of the change. syzbot's patch testing also completed without reproducing the hang. |
Risk And Classification
EPSS: 0.001950000 probability, percentile 0.092860000 (date 2026-09-07)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected 1a56cd972ce121b6cf2517a47a578782bbd2ec95 119a2f053242ed75bdd2ebc95baf3ae7db6ccacf git | Not specified |
| CNA | Linux | Linux | affected 1be97463696c7291a3e1547614e96432b0bd3add 61631352a5b405c89be579de00903b72e6888aa4 git | Not specified |
| CNA | Linux | Linux | affected 65f8b80053a1b2fd602daa6814e62d6fa90e5e9b 8865cd664484517703df5c18a965dc3227572b87 git | Not specified |
| CNA | Linux | Linux | affected 65f8b80053a1b2fd602daa6814e62d6fa90e5e9b a40c45268f4358207aa9c53764fed2e05f62986a git | Not specified |
| CNA | Linux | Linux | affected 65f8b80053a1b2fd602daa6814e62d6fa90e5e9b 889ec86464d261f026f6c334040cfc6c58c99d58 git | Not specified |
| CNA | Linux | Linux | affected 65f8b80053a1b2fd602daa6814e62d6fa90e5e9b 4902a5cba21aeaf91e6b29e20e0967a5f6abdcd9 git | Not specified |
| CNA | Linux | Linux | affected 65f8b80053a1b2fd602daa6814e62d6fa90e5e9b 55ee6533c1db7f7656fa8dd19637f3f8b8c08dc5 git | Not specified |
| CNA | Linux | Linux | affected 65f8b80053a1b2fd602daa6814e62d6fa90e5e9b dbd4aea175ad3c46436acb251e817b4374628072 git | Not specified |
| CNA | Linux | Linux | affected 65f8b80053a1b2fd602daa6814e62d6fa90e5e9b 54b6bd40898de7906acb2bccc9a96d1b8e6b4323 git | Not specified |
| CNA | Linux | Linux | affected 98953044b3cdb2cb7d82e7365b659e2ed4f4ca4d git | Not specified |
| CNA | Linux | Linux | affected af8ecc8d20e72130771cc076bce7fcf17ccda6c4 git | Not specified |
| CNA | Linux | Linux | affected c6fac5cf5a5098732623bcd00a8a3eb9f5465144 git | Not specified |
| CNA | Linux | Linux | affected 96fa141fa295ae9428da73c56c9852053b575c04 git | Not specified |
| CNA | Linux | Linux | affected 5.10.163 5.10.267 semver | Not specified |
| CNA | Linux | Linux | affected 5.15.61 5.15.218 semver | Not specified |
| CNA | Linux | Linux | affected 4.19.270 4.20 semver | Not specified |
| CNA | Linux | Linux | affected 5.4.229 5.5 semver | Not specified |
| CNA | Linux | Linux | affected 5.18.18 5.19 semver | Not specified |
| CNA | Linux | Linux | affected 5.19.2 5.20 semver | Not specified |
| CNA | Linux | Linux | affected 6.0 | Not specified |
| CNA | Linux | Linux | unaffected 6.0 semver | Not specified |
| CNA | Linux | Linux | unaffected 5.10.267 5.10.* semver | Not specified |
| CNA | Linux | Linux | unaffected 5.15.218 5.15.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.1.185 6.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.6.154 6.6.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.12.106 6.12.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.18.47 6.18.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.1.11 7.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.2.1 7.2.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.3-rc1 * original_commit_for_fix | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| git.kernel.org/stable/c/dbd4aea175ad3c46436acb251e817b4374628072 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/889ec86464d261f026f6c334040cfc6c58c99d58 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/a40c45268f4358207aa9c53764fed2e05f62986a | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/4902a5cba21aeaf91e6b29e20e0967a5f6abdcd9 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/54b6bd40898de7906acb2bccc9a96d1b8e6b4323 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/8865cd664484517703df5c18a965dc3227572b87 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/61631352a5b405c89be579de00903b72e6888aa4 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/119a2f053242ed75bdd2ebc95baf3ae7db6ccacf | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/55ee6533c1db7f7656fa8dd19637f3f8b8c08dc5 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.