CVE-2026-92503— ext4: fix ABBA deadlock in ext4_xattr_inode_cache_find()
Quick assessment
Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
在 Linux 内核中，以下漏洞已得到修复： ext4：修复 ext4_xattr_inode_cache_find() 中的 ABBA 死锁 Syzbot 和 stress-ng 报告了 ext4 在执行并发扩展属性（xattr）负载（使用 ea_inode 挂载/格式化选项时）时出现的 ABBA 死锁问题。 死锁发生在运行中的事务线程与驱逐（eviction）线程之间： 任务 1（stress-ng）：持有对共享的 （ ）的引用，并调用 -> 来获取对应的 EA inode。由于该 EA inode 当前正处于
Possible ATT&CK Techniques 1 AI
T1614 · System Location DiscoveryAffected Version Matrix 12
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| Linux | Linux | 0a46ef234756dca04623b7591e8ebb3440622f0b< 7720fddd1fe344d14be258a2028f74ebf1569511 |
affected |
0a46ef234756dca04623b7591e8ebb3440622f0b< 03438084a7b8621fb5c762dd3d04cff5f2630fb2 |
affected | ||
0752e7fb549d90c33b4d4186f11cfd25a556d1dd |
affected | ||
737fb7853acd5bc8984f6f42e4bfba3334be8ae1 |
affected | ||
111103907234bffd0a34fba070ad9367de058752 |
affected | ||
6.1.107< 6.2 |
affected | ||
6.6.47< 6.7 |
affected | ||
6.9.7< 6.10 |
affected | ||
| … +4 more rows | |||
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I. Basic Information for CVE-2026-92503
Vulnerability Information
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Vulnerability Title
ext4: fix ABBA deadlock in ext4_xattr_inode_cache_find()
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Affected Products
II. Public POCs for CVE-2026-92503
| # | POC Description | Source Link | Shenlong Link |
|---|
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Patches & Fixes for CVE-2026-92503 (2)
Same Patch Batch · Linux · 2026-09-17 · 600 CVEs total
| CVE-2026-92489 | 9.8 CRITICAL | xfrm: Fix skb double-free in xfrm_dev_direct_output() |
| CVE-2026-90235 | 9.8 CRITICAL | sunrpc: xprtsock: annotate shared socket callbacks with READ_ONCE/WRITE_ONCE |
| CVE-2026-90173 | 9.8 CRITICAL | smb: smbdirect: free completion queues with ib_free_cq() |
| CVE-2026-90104 | 9.8 CRITICAL | NFSv4.1: zero referring call lists before decoding |
| CVE-2026-90151 | 9.8 CRITICAL | NFSv4: remove callback IDR entry on client allocation failure |
| CVE-2026-90110 | 9.4 CRITICAL | inetpeer: randomize RB-tree node comparison using SipHash |
| CVE-2026-90230 | 9.1 CRITICAL | nvmet: fix heap out-of-bounds read in nvmet_auth_negotiate() |
| CVE-2026-90414 | 9.1 CRITICAL | IB/isert: reject PDUs declaring more data than was received |
| CVE-2026-90413 | 9.1 CRITICAL | IB/isert: reject login PDUs declaring more data than was received |
| CVE-2026-90367 | 8.8 HIGH | wifi: mt76: mt7996: hold dev->mt76.mutex while disabling tx worker in SER |
| CVE-2026-90329 | 8.8 HIGH | HID: synchronize input before cleaning up a failed probe |
| CVE-2026-93189 | 8.8 HIGH | HID: core: quiesce input in hid_hw_stop() to prevent use-after-free |
| CVE-2026-90240 | 8.8 HIGH | iommu/vt-d: Flush context cache with correct SID when tearing down aliases |
| CVE-2026-90357 | 8.8 HIGH | wifi: mt76: mt7915: unlink TWT flow if the MCU rejects the agreement |
| CVE-2026-90286 | 8.8 HIGH | drm/amdgpu/gfx6: Use PFP on the compute queues too |
| CVE-2026-93042 | 8.8 HIGH | dmaengine: dw-edma: Terminate all descriptors without callbacks |
| CVE-2026-90256 | 8.8 HIGH | Bluetooth: L2CAP: use proto_lock for l2cap_data to fix l2cap_disconn_ind |
| CVE-2026-90380 | 8.8 HIGH | wifi: mt76: mt792x: fix use-after-free in mt76_rx_poll_complete |
| CVE-2026-90381 | 8.8 HIGH | wifi: mt76: fix handling channel context with different bands in mt76_switch_vif_chanctx() |
| CVE-2026-90425 | 8.8 HIGH | iommu/tegra241-cmdqv: Require exactly one Stream ID for a vSID |
Showing top 20 of 600 CVEs. View all on vendor page → →
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V. Comments for CVE-2026-92503
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