---
id: CVE-2026-92503
title: |-
  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_in…
summary: |-
  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_in…
severity: none
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: '2026-09-17'
sourceUpdated: '2026-09-17T17:17:52.820'
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/7720fddd1fe344d14be258a2028f74ebf1569511'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-17T16:21:47.781Z'
epss: 0.00189
epssPercentile: 0.0885
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.