Vulnerability-Lookup

GHSA-QFC6-3G3R-6RJJ

Vulnerability from github – Published: 2026-10-14 15:32 – Updated: 2026-10-14 15:32

Details

In the Linux kernel, the following vulnerability has been resolved:

locking/lockdep: Invalidate stale class_cache entries for zapped classes

syzbot reported a lockdep splat hitting DEBUG_LOCKS_WARN_ON(1) in hlock_class() due to an invalid class_idx:

WARNING: kernel/locking/lockdep.c:238 at __lock_acquire+0x382/0x2cf0 kernel/locking/lockdep.c:5203 Workqueue: wg-crypt-wg0 wg_packet_tx_worker RIP: 0010:hlock_class kernel/locking/lockdep.c:238 [inline] RIP: 0010:check_wait_context kernel/locking/lockdep.c:4870 [inline] RIP: 0010:__lock_acquire+0x389/0x2cf0 kernel/locking/lockdep.c:5203 Call Trace: lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5886 _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:173 tcp_tsq_handler+0x29/0x200 net/ipv4/tcp_output.c:1291 tcp_tsq_workfn+0x384/0x410 net/ipv4/tcp_output.c:1325 ...

When a lock class is zapped (e.g. during module unload or key unregistration), zap_class() clears the class's bit in lock_classes_in_use and removes it from the class hash table. However, existing lockdep_map instances embedded in data structures may still retain a pointer to the zapped class in their class_cache[] array.

When __lock_acquire() subsequently runs on such a lock, it finds lock->class_cache[subclass] != NULL, skipping register_lock_class() and assigning hlock->class_idx to the index of the zapped class. When check_wait_context() or hlock_class() inspects the held_lock, it finds !test_bit(class_idx, lock_classes_in_use) and warns. Furthermore, if the zapped slot is subsequently re-allocated to an unrelated lock key, the stale class_cache entry would erroneously match the unrelated class (ABA issue).

Add lock_class_cache_is_valid() to validate that the cached class is within lock_classes bounds, still allocated in lock_classes_in_use (using uninstrumented arch_test_bit() in __always_inline context so it is safe in noinstr contexts like match_held_lock()), and that class->key matches the expected subkey (taking lockdep_set_subclass() overrides into account). Also use READ_ONCE()/WRITE_ONCE() when accessing class_cache[]. If the entry is invalid or stale, fall back to register_lock_class() / look_up_lock_class().

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{
  "affected": [],
  "aliases": [
    "CVE-2026-98398"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-14T14:17:50Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nlocking/lockdep: Invalidate stale class_cache entries for zapped classes\n\nsyzbot reported a lockdep splat hitting DEBUG_LOCKS_WARN_ON(1) in\nhlock_class() due to an invalid class_idx:\n\n  WARNING: kernel/locking/lockdep.c:238 at __lock_acquire+0x382/0x2cf0 kernel/locking/lockdep.c:5203\n  Workqueue: wg-crypt-wg0 wg_packet_tx_worker\n  RIP: 0010:hlock_class kernel/locking/lockdep.c:238 [inline]\n  RIP: 0010:check_wait_context kernel/locking/lockdep.c:4870 [inline]\n  RIP: 0010:__lock_acquire+0x389/0x2cf0 kernel/locking/lockdep.c:5203\n  Call Trace:\n   \u003cIRQ\u003e\n   lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5886\n   _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:173\n   tcp_tsq_handler+0x29/0x200 net/ipv4/tcp_output.c:1291\n   tcp_tsq_workfn+0x384/0x410 net/ipv4/tcp_output.c:1325\n   ...\n\nWhen a lock class is zapped (e.g. during module unload or key\nunregistration), zap_class() clears the class\u0027s bit in\nlock_classes_in_use and removes it from the class hash table.\nHowever, existing lockdep_map instances embedded in data structures\nmay still retain a pointer to the zapped class in their class_cache[]\narray.\n\nWhen __lock_acquire() subsequently runs on such a lock, it finds\nlock-\u003eclass_cache[subclass] != NULL, skipping register_lock_class()\nand assigning hlock-\u003eclass_idx to the index of the zapped class. When\ncheck_wait_context() or hlock_class() inspects the held_lock, it finds\n!test_bit(class_idx, lock_classes_in_use) and warns. Furthermore, if\nthe zapped slot is subsequently re-allocated to an unrelated lock key,\nthe stale class_cache entry would erroneously match the unrelated\nclass (ABA issue).\n\nAdd lock_class_cache_is_valid() to validate that the cached class is\nwithin lock_classes bounds, still allocated in lock_classes_in_use\n(using uninstrumented arch_test_bit() in __always_inline context so it\nis safe in noinstr contexts like match_held_lock()), and that\nclass-\u003ekey matches the expected subkey (taking lockdep_set_subclass()\noverrides into account). Also use READ_ONCE()/WRITE_ONCE() when\naccessing class_cache[].  If the entry is invalid or stale, fall back\nto register_lock_class() / look_up_lock_class().",
  "id": "GHSA-qfc6-3g3r-6rjj",
  "modified": "2026-10-14T15:32:19Z",
  "published": "2026-10-14T15:32:19Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98398"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/02c6be7d675b21d81f0ba3a524346850a8c0e3bf"
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    },
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    {
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      "url": "https://git.kernel.org/stable/c/baa320fbb2f9fea50f5632a307da8ce84fbef5bd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c7acfb04c7e2e2dea248282b21373d93296644dd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f63c86e9d267629758adaba18579e784ddd63c32"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f8a1281ab82df5b51fd0384354d4b21daf2b7af0"
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}

CVE-2026-98398 (GCVE-0-2026-98398)

Vulnerability from cvelistv5 – Published: 2026-10-14 13:25 – Updated: 2026-10-19 09:18

Title

locking/lockdep: Invalidate stale class_cache entries for zapped classes

Summary

In the Linux kernel, the following vulnerability has been resolved: locking/lockdep: Invalidate stale class_cache entries for zapped classes syzbot reported a lockdep splat hitting DEBUG_LOCKS_WARN_ON(1) in hlock_class() due to an invalid class_idx: WARNING: kernel/locking/lockdep.c:238 at __lock_acquire+0x382/0x2cf0 kernel/locking/lockdep.c:5203 Workqueue: wg-crypt-wg0 wg_packet_tx_worker RIP: 0010:hlock_class kernel/locking/lockdep.c:238 [inline] RIP: 0010:check_wait_context kernel/locking/lockdep.c:4870 [inline] RIP: 0010:__lock_acquire+0x389/0x2cf0 kernel/locking/lockdep.c:5203 Call Trace: <IRQ> lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5886 _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:173 tcp_tsq_handler+0x29/0x200 net/ipv4/tcp_output.c:1291 tcp_tsq_workfn+0x384/0x410 net/ipv4/tcp_output.c:1325 ... When a lock class is zapped (e.g. during module unload or key unregistration), zap_class() clears the class's bit in lock_classes_in_use and removes it from the class hash table. However, existing lockdep_map instances embedded in data structures may still retain a pointer to the zapped class in their class_cache[] array. When __lock_acquire() subsequently runs on such a lock, it finds lock->class_cache[subclass] != NULL, skipping register_lock_class() and assigning hlock->class_idx to the index of the zapped class. When check_wait_context() or hlock_class() inspects the held_lock, it finds !test_bit(class_idx, lock_classes_in_use) and warns. Furthermore, if the zapped slot is subsequently re-allocated to an unrelated lock key, the stale class_cache entry would erroneously match the unrelated class (ABA issue). Add lock_class_cache_is_valid() to validate that the cached class is within lock_classes bounds, still allocated in lock_classes_in_use (using uninstrumented arch_test_bit() in __always_inline context so it is safe in noinstr contexts like match_held_lock()), and that class->key matches the expected subkey (taking lockdep_set_subclass() overrides into account). Also use READ_ONCE()/WRITE_ONCE() when accessing class_cache[]. If the entry is invalid or stale, fall back to register_lock_class() / look_up_lock_class().

Severity

No CVSS data available.

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 7056 records in the last 180 days details

References

7 references

URL	Tags
https://git.kernel.org/stable/c/f8a1281ab82df5b51…
https://git.kernel.org/stable/c/1c9d664e2e067fca6…
https://git.kernel.org/stable/c/6bc345f6d81ebe22e…
https://git.kernel.org/stable/c/f63c86e9d26762975…
https://git.kernel.org/stable/c/c7acfb04c7e2e2dea…
https://git.kernel.org/stable/c/baa320fbb2f9fea50…
https://git.kernel.org/stable/c/02c6be7d675b21d81…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: a0b0fd53e1e67639b303b15939b9c653dbe7a8c4 , < f8a1281ab82df5b51fd0384354d4b21daf2b7af0 (git) Affected: a0b0fd53e1e67639b303b15939b9c653dbe7a8c4 , < 1c9d664e2e067fca69e5a41d68e23bbc66a583fe (git) Affected: a0b0fd53e1e67639b303b15939b9c653dbe7a8c4 , < 6bc345f6d81ebe22e0f355c2a21d7e29691f9332 (git) Affected: a0b0fd53e1e67639b303b15939b9c653dbe7a8c4 , < f63c86e9d267629758adaba18579e784ddd63c32 (git) Affected: a0b0fd53e1e67639b303b15939b9c653dbe7a8c4 , < c7acfb04c7e2e2dea248282b21373d93296644dd (git) Affected: a0b0fd53e1e67639b303b15939b9c653dbe7a8c4 , < baa320fbb2f9fea50f5632a307da8ce84fbef5bd (git) Affected: a0b0fd53e1e67639b303b15939b9c653dbe7a8c4 , < 02c6be7d675b21d81f0ba3a524346850a8c0e3bf (git)
Linux	Linux	Affected: 5.1 Unaffected: 0 , < 5.1 (semver) Unaffected: 5.15.222 , ≤ 5.15.* (semver) Unaffected: 6.1.189 , ≤ 6.1.* (semver) Unaffected: 6.6.158 , ≤ 6.6.* (semver) Unaffected: 6.12.111 , ≤ 6.12.* (semver) Unaffected: 6.18.53 , ≤ 6.18.* (semver) Unaffected: 7.2.7 , ≤ 7.2.* (semver) Unaffected: 7.3 , ≤ * (original_commit_for_fix)

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{
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}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
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