CVE-2026-92503
- Source
- https://cve.org/CVERecord?id=CVE-2026-92503
- Import Source
- https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-92503.json
- JSON Data
- https://api.osv.dev/v1/vulns/CVE-2026-92503
- Downstream
- Related
- Published
- 2026-09-17T16:10:16Z
- Modified
- 2026-10-08T02:52:31Z
- Summary
- ext4: fix ABBA deadlock in ext4_xattr_inode_cache_find()
- Details
-
In the Linux kernel, the following vulnerability has been resolved:
ext4: fix ABBA deadlock in ext4_xattr_inode_cache_find()
Syzbot/stress-ng reported an ABBA deadlock in ext4 when exercising concurrent xattr workloads (using the ea_inode mount/format option).
The deadlock occurs between the running transaction and the eviction thread:
- Task 1 (stress-ng): Holds a reference to a shared mbcache_entry (ce) and calls ext4_xattr_inode_cache_find() -> ext4_iget() to retrieve the corresponding EA inode. Since the EA inode is currently being evicted, ext4_iget() blocks in __wait_on_freeing_inode() waiting for eviction to complete.
- Task 2 (eviction thread): Currently evicting the same EA inode in ext4_evict_ea_inode(). It calls mb_cache_entry_wait_unused(oe) which blocks waiting for Task 1 to release the reference to the mbcache_entry.
To break this deadlock, implement a new ext4_iget() configuration flag named EXT4_IGET_NOWAIT. When set, perform a non-blocking lookup of the inode via VFS's find_inode_nowait() API.
If the inode is currently being evicted (marked with I_FREEING or I_WILL_FREE) or created (I_CREATING), or if it is not present in the VFS inode cache (cache miss), simply skip it (returning -ENOENT) rather than waiting for eviction/creation to complete, breaking the ABBA cycle.
Since we return -ENOENT immediately on a cache miss, we never attempt to allocate a new inode or call iget_locked(), completely eliminating any TOCTOU race window.
If the returned inode is I_NEW, wait for its initialization to clear via wait_on_new_inode(). If initialization fails and the inode is unhashed during wait_on_new_inode() waking up (e.g., due to an I/O read error in another thread), safely drop the reference and return -ENOENT. This unhashed check is executed unconditionally on all cache-hit pathways to properly handle concurrent initialization failures.
Finally, standard validation checks (including is_bad_inode, EXT4_EA_INODE_FL, file_acl, and xattr flags) are executed as normal inside check_igot_inode() to fully guarantee VFS-layer safety.
In ext4_xattr_inode_cache_find(), invoke ext4_iget() with the new EXT4_IGET_NOWAIT flag to perform the non-blocking cache search.
- Database specific
{ "cna_assigner": "Linux", "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/92xxx/CVE-2026-92503.json" }- References
-
- https://git.kernel.org/stable/c/03438084a7b8621fb5c762dd3d04cff5f2630fb2
- https://git.kernel.org/stable/c/7720fddd1fe344d14be258a2028f74ebf1569511
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/92xxx/CVE-2026-92503.json
- https://nvd.nist.gov/vuln/detail/CVE-2026-92503
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Affected packages
Git / git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Affected ranges
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced0a46ef234756dca04623b7591e8ebb3440622f0bFixed7720fddd1fe344d14be258a2028f74ebf1569511Fixed03438084a7b8621fb5c762dd3d04cff5f2630fb2
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced6.1.107Fixed6.2
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced6.6.47Fixed6.7
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced6.9.7Fixed6.10
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced0752e7fb549d90c33b4d4186f11cfd25a556d1dd
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced737fb7853acd5bc8984f6f42e4bfba3334be8ae1
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced111103907234bffd0a34fba070ad9367de058752