The following commit has been merged into the locking/core branch of tip:
Commit-ID: 7577e00b9ab506202b9f1a33de3cc8cc6413a4db
Gitweb: https://git.kernel.org/tip/7577e00b9ab506202b9f1a33de3cc8cc6413a4db
Author: Naveen Kumar Chaudhary <naveen.osdev@gmail.com>
AuthorDate: Thu, 11 Jun 2026 23:08:17 +05:30
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Fri, 31 Jul 2026 10:32:24 +02:00
locking/lockdep: Fix NULL pointer dereference in __lock_set_class()
register_lock_class() can return NULL when the lock class pool is
exhausted, graph_lock() fails, or key validation fails. However,
__lock_set_class() uses the return value directly in pointer arithmetic
without a NULL check:
class = register_lock_class(lock, subclass, 0);
hlock->class_idx = class - lock_classes;
If class is NULL, this computes a wild offset that corrupts
hlock->class_idx. The subsequent reacquire_held_locks() call will
invoke hlock_class() with this corrupted index, leading to a NULL or
out-of-bounds pointer dereference.
Add the missing NULL check, consistent with how __lock_acquire() already
handles this case at the same call site.
Fixes: 64aa348edc61 ("lockdep: lock_set_subclass - reset a held lock's subclass")
Signed-off-by: Naveen Kumar Chaudhary <naveen.osdev@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Waiman Long <longman@redhat.com>
Reviewed-by: Dmitry Ilvokhin <d@ilvokhin.com>
Link: https://patch.msgid.link/h2kfw43n4527x6mgi2lwpz2rieqnfzgictpv4wr5nyfjkc47co@2r5vz4uz44db
---
kernel/locking/lockdep.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index ff4bbf1..25d77d4 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -5453,6 +5453,8 @@ __lock_set_class(struct lockdep_map *lock, const char *name,
lock->wait_type_outer,
lock->lock_type);
class = register_lock_class(lock, subclass, 0);
+ if (!class)
+ return 0;
hlock->class_idx = class - lock_classes;
curr->lockdep_depth = i;