{"id":"CVE-2026-98398","title":"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 inva…","summary":"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 inva…","severity":"none","published":"2026-10-14","updated":"2026-10-14","sourceUpdated":"2026-10-14T14:17:50.760","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-98398","references":[{"url":"https://git.kernel.org/stable/c/02c6be7d675b21d81f0ba3a524346850a8c0e3bf","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/1c9d664e2e067fca69e5a41d68e23bbc66a583fe","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/6bc345f6d81ebe22e0f355c2a21d7e29691f9332","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/baa320fbb2f9fea50f5632a307da8ce84fbef5bd","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/c7acfb04c7e2e2dea248282b21373d93296644dd","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f63c86e9d267629758adaba18579e784ddd63c32","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f8a1281ab82df5b51fd0384354d4b21daf2b7af0","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd"],"ingestedAt":"2026-10-14T15:36:13.979Z","slug":"CVE-2026-98398","body":"## Overview\n\nIn 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   <IRQ>\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's 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->class_cache[subclass] != NULL, skipping register_lock_class()\nand assigning hlock->class_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->key 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().\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}