[PATCH v4 1/2] locking/lockdep: Forcing subclasses to have same name pointer as their parent class

[botta633 <bottaawesome633@gmail.com>]

From: Ahmed Ehab <bottaawesome633@gmail.com>

Preventing lockdep_set_subclass from creating a new instance of the
string literal. Hence, we will always have the same class->name among
parent and subclasses. This prevents kernel panics when looking up a
lock class while comparing class locks and class names.

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>
---
 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 08b0d1d9d78b..df8fa5929de7 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)
-- 
2.45.2