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

[Boqun Feng]

On Mon, Jul 15, 2024 at 04:26:37PM +0300, botta633 wrote:
> From: Ahmed Ehab <bottaawesome633@xxxxxxxxx>
> 
> 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@xxxxxxxxxxxxxxxxxxxxxxxxx>
> Fixes: de8f5e4f2dc1f ("lockdep: Introduce wait-type checks")
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Ahmed Ehab <bottaawesome633@xxxxxxxxx>

This looks good to me.

Regards,
Boqun

> ---
> v3->v4:
>     - Fixed subject line truncation.
> 
>  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