The following commit has been merged into the locking/core branch of tip:

Commit-ID: d7fe143cb115076fed0126ad8cf5ba6c3e575e43 Gitweb: https://git.kernel.org/tip/d7fe143cb115076fed0126ad8cf5ba6c3e575e43 Author: Ahmed Ehab bottaawesome633@gmail.com AuthorDate: Sun, 25 Aug 2024 01:10:30 +03:00 Committer: Boqun Feng boqun.feng@gmail.com CommitterDate: Thu, 17 Oct 2024 20:07:23 -07:00

locking/lockdep: Avoid creating new name string literals in lockdep_set_subclass()

Syzbot reports a problem that a warning will be triggered while searching a lock class in look_up_lock_class().

The cause of the issue is that a new name is created and used by lockdep_set_subclass() instead of using the existing one. This results in a lock instance has a different name pointer than previous registered one stored in lock class, and WARN_ONCE() is triggered because of that in look_up_lock_class().

To fix this, change lockdep_set_subclass() to use the existing name instead of a new one. Hence, no new name will be created by lockdep_set_subclass(). Hence, the warning is avoided.

[boqun: Reword the commit log to state the correct issue]

Reported-by: syzbot+7f4a6f7f7051474e40ad@syzkaller.appspotmail.com Fixes: de8f5e4f2dc1f ("lockdep: Introduce wait-type checks") Cc: stable@vger.kernel.org Signed-off-by: Ahmed Ehab bottaawesome633@gmail.com Signed-off-by: Boqun Feng boqun.feng@gmail.com Link: https://lore.kernel.org/lkml/20240824221031.7751-1-bottaawesome633@gmail.com... --- include/linux/lockdep.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index 217f7ab..67964dc 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -173,7 +173,7 @@ static inline void lockdep_init_map(struct lockdep_map *lock, const char *name, (lock)->dep_map.lock_type)

#define lockdep_set_subclass(lock, sub) \ - lockdep_init_map_type(&(lock)->dep_map, #lock, (lock)->dep_map.key, sub,\ + lockdep_init_map_type(&(lock)->dep_map, (lock)->dep_map.name, (lock)->dep_map.key, sub,\ (lock)->dep_map.wait_type_inner, \ (lock)->dep_map.wait_type_outer, \ (lock)->dep_map.lock_type)