Re: [PATCH] block, bfq: fix waker_bfqq UAF after bfq_split_bfqq()

[Jan Kara]

On Thu 09-01-25 09:32:08, Yu Kuai wrote:
> Hi,
> 
> 在 2025/01/08 22:42, Jan Kara 写道:
> > 
> > 
> > >   			 */
> > >   			if (bfqq_process_refs(waker_bfqq) == 1)
> > >   				return NULL;
> > > -			break;
> > > +
> > > +			return waker_bfqq;
> > 
> > So how do you know bfqq_process_refs(waker_bfqq) is not 0 in this case?
> 
> Because in this case, waker_bfqq is in the merge chain of bfqq, and bfqq
> is obtained frm the current process, which means waker_bfqq should have
> at least one process reference that is from current thread.

Ah, right. Thanks for explanation. The except for the typo the patch looks
good to me. Feel free to add:

Reviewed-by: Jan Kara <jack@xxxxxxx>

(although I can see Jens has already picked up the patch so probably this
is immaterial).

								Honza
-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR