{"api_version":"1","generated_at":"2026-09-17T23:37:50+00:00","cve":"CVE-2026-92503","urls":{"html":"https://cve.report/CVE-2026-92503","api":"https://cve.report/api/cve/CVE-2026-92503.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-92503","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-92503"},"summary":{"title":"ext4: fix ABBA deadlock in ext4_xattr_inode_cache_find()","description":"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_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.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-17 17:17:52","updated_at":"2026-09-17 17:17:52"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/7720fddd1fe344d14be258a2028f74ebf1569511","name":"https://git.kernel.org/stable/c/7720fddd1fe344d14be258a2028f74ebf1569511","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/03438084a7b8621fb5c762dd3d04cff5f2630fb2","name":"https://git.kernel.org/stable/c/03438084a7b8621fb5c762dd3d04cff5f2630fb2","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-92503","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-92503","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 0a46ef234756dca04623b7591e8ebb3440622f0b 7720fddd1fe344d14be258a2028f74ebf1569511 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 0a46ef234756dca04623b7591e8ebb3440622f0b 03438084a7b8621fb5c762dd3d04cff5f2630fb2 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 0752e7fb549d90c33b4d4186f11cfd25a556d1dd git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 737fb7853acd5bc8984f6f42e4bfba3334be8ae1 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 111103907234bffd0a34fba070ad9367de058752 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.1.107 6.2 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.6.47 6.7 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.9.7 6.10 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.10","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.10 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.6 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/ext4/ext4.h","fs/ext4/inode.c","fs/ext4/xattr.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"7720fddd1fe344d14be258a2028f74ebf1569511","status":"affected","version":"0a46ef234756dca04623b7591e8ebb3440622f0b","versionType":"git"},{"lessThan":"03438084a7b8621fb5c762dd3d04cff5f2630fb2","status":"affected","version":"0a46ef234756dca04623b7591e8ebb3440622f0b","versionType":"git"},{"status":"affected","version":"0752e7fb549d90c33b4d4186f11cfd25a556d1dd","versionType":"git"},{"status":"affected","version":"737fb7853acd5bc8984f6f42e4bfba3334be8ae1","versionType":"git"},{"status":"affected","version":"111103907234bffd0a34fba070ad9367de058752","versionType":"git"},{"lessThan":"6.2","status":"affected","version":"6.1.107","versionType":"semver"},{"lessThan":"6.7","status":"affected","version":"6.6.47","versionType":"semver"},{"lessThan":"6.10","status":"affected","version":"6.9.7","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/ext4/ext4.h","fs/ext4/inode.c","fs/ext4/xattr.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.10"},{"lessThan":"6.10","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.6","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.6","versionStartIncluding":"6.10","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"6.10","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1.107","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6.47","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.9.7","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"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_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."}],"providerMetadata":{"dateUpdated":"2026-09-17T16:10:16.062Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/7720fddd1fe344d14be258a2028f74ebf1569511"},{"url":"https://git.kernel.org/stable/c/03438084a7b8621fb5c762dd3d04cff5f2630fb2"}],"title":"ext4: fix ABBA deadlock in ext4_xattr_inode_cache_find()","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-92503","datePublished":"2026-09-17T16:10:16.062Z","dateReserved":"2026-09-16T12:21:13.872Z","dateUpdated":"2026-09-17T16:10:16.062Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-17 17:17:52","lastModifiedDate":"2026-09-17 17:17:52","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"92503","Ordinal":"1","Title":"ext4: fix ABBA deadlock in ext4_xattr_inode_cache_find()","CVE":"CVE-2026-92503","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"92503","Ordinal":"1","NoteData":"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_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.","Type":"Description","Title":"ext4: fix ABBA deadlock in ext4_xattr_inode_cache_find()"}]}}}