{"id":"CVE-2026-92503","title":"In the Linux kernel, the following vulnerability has been resolved:\n\next4: fix ABBA deadlock in ext4_xattr_inode_cache_find()\n\nSyzbot/stress-ng reported an ABBA deadlock in ext4 when exercising\nconcurrent xattr workloads (using the ea_in…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\next4: fix ABBA deadlock in ext4_xattr_inode_cache_find()\n\nSyzbot/stress-ng reported an ABBA deadlock in ext4 when exercising\nconcurrent xattr workloads (using the ea_in…","severity":"medium","vendor":"Linux","product":"Linux","affected":["Linux >= 0a46ef234756dca04623b7591e8ebb3440622f0b < 7720fddd1fe344d14be258a2028f74ebf1569511","Linux >= 0a46ef234756dca04623b7591e8ebb3440622f0b < 03438084a7b8621fb5c762dd3d04cff5f2630fb2","Linux 0752e7fb549d90c33b4d4186f11cfd25a556d1dd","Linux 737fb7853acd5bc8984f6f42e4bfba3334be8ae1","Linux 111103907234bffd0a34fba070ad9367de058752","Linux >= 6.1.107 < 6.2","Linux >= 6.6.47 < 6.7","Linux >= 6.9.7 < 6.10","Linux 6.10"],"published":"2026-09-17","updated":"2026-10-15","sourceUpdated":"2026-10-15T11:18:04.717","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-92503","references":[{"url":"https://git.kernel.org/stable/c/03438084a7b8621fb5c762dd3d04cff5f2630fb2","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/074d0620401974cbfa9b63684cdfae99c7b2059c","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/7720fddd1fe344d14be258a2028f74ebf1569511","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-92503.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-92503"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2536181"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-92503"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-92503"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-92503.mbox"},{"url":"https://git.kernel.org/stable/c/29a2a166450a3e89f61a486033b10cf170fde8b0"},{"url":"https://git.kernel.org/stable/c/d3b19b318e0e0483180d15f1d9f5e807a1fb59d5"}],"tags":["nvd","cve.org","csaf","vex","red-hat"],"epss":0.00213,"epssPercentile":0.11563,"ingestedAt":"2026-09-17T16:21:47.781Z","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cvssSource":"vendor","cwe":["CWE-833"],"slug":"CVE-2026-92503","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\next4: fix ABBA deadlock in ext4_xattr_inode_cache_find()\n\nSyzbot/stress-ng reported an ABBA deadlock in ext4 when exercising\nconcurrent xattr workloads (using the ea_inode mount/format option).\n\nThe deadlock occurs between the running transaction and the eviction\nthread:\n- Task 1 (stress-ng): Holds a reference to a shared mbcache_entry (ce)\n  and calls ext4_xattr_inode_cache_find() -> ext4_iget() to retrieve\n  the corresponding EA inode. Since the EA inode is currently being\n  evicted, ext4_iget() blocks in __wait_on_freeing_inode() waiting for\n  eviction to complete.\n- Task 2 (eviction thread): Currently evicting the same EA inode in\n  ext4_evict_ea_inode(). It calls mb_cache_entry_wait_unused(oe) which\n  blocks waiting for Task 1 to release the reference to the mbcache_entry.\n\nTo break this deadlock, implement a new ext4_iget() configuration flag\nnamed EXT4_IGET_NOWAIT. When set, perform a non-blocking lookup of the\ninode via VFS's find_inode_nowait() API.\n\nIf the inode is currently being evicted (marked with I_FREEING or\nI_WILL_FREE) or created (I_CREATING), or if it is not present in the VFS\ninode cache (cache miss), simply skip it (returning -ENOENT) rather than\nwaiting for eviction/creation to complete, breaking the ABBA cycle.\n\nSince we return -ENOENT immediately on a cache miss, we never attempt to\nallocate a new inode or call iget_locked(), completely eliminating any\nTOCTOU race window.\n\nIf the returned inode is I_NEW, wait for its initialization to clear via\nwait_on_new_inode(). If initialization fails and the inode is unhashed\nduring wait_on_new_inode() waking up (e.g., due to an I/O read error in\nanother thread), safely drop the reference and return -ENOENT. This\nunhashed check is executed unconditionally on all cache-hit pathways to\nproperly handle concurrent initialization failures.\n\nFinally, standard validation checks (including is_bad_inode,\nEXT4_EA_INODE_FL, file_acl, and xattr flags) are executed as normal inside\ncheck_igot_inode() to fully guarantee VFS-layer safety.\n\nIn ext4_xattr_inode_cache_find(), invoke ext4_iget() with the new\nEXT4_IGET_NOWAIT flag to perform the non-blocking cache search.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, … · updated 2026-10-20 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-92503.json)","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":225535,"id":"CVE-2026-92503","ts":1792498288784,"field":"cvss","old":null,"new":"5.5"},{"seq":225534,"id":"CVE-2026-92503","ts":1792498288784,"field":"severity","old":"none","new":"medium"}]}