Hello,
Our static analysis tool finds a possible null-pointer dereference in
bfq-iosched.c in Linux 5.14.0-rc3:
The variable bfqq is checked in:
5920: waiting = bfqq && bfq_bfqq_wait_request(bfqq);
This indicates that bfqq can be NULL.
But the address of its field fifo, which is an illegal pointer, is
dereferenced in the function list_add_tail():
5925: list_add_tail(&rq->queuelist, &bfqq->fifo);
The pointer bfqq is also dereferenced in the function bfq_rq_enqueued()
which is called at line 5927.
Some dereference operations are:
5826: bfqq->meta_pending++;
5828: bfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
I am not quite sure whether this possible null-pointer dereference is
real and how to fix it if it is real.
Any feedback would be appreciated, thanks!
Reported-by: TOTE Robot <oslab@xxxxxxxxxxxxxxx>
Best wishes,
Tuo Li
