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null_blk: fix use-after-free problem

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end_cmd finishes request associated with nullb_cmd struct, so we
should save pointer to request_queue in a local variable before
calling end_cmd.

The problem was causes general protection fault with slab poisoning
enabled.

Fixes: 8b70f45e2e ("null_blk: restart request processing on completion handler")
Tested-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Mike Krinkin <krinkin.m.u@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Mike Krinkin 2015-07-19 09:53:17 +03:00 committed by Jens Axboe
parent d725e66c06
commit 21974061cf
1 changed files with 9 additions and 9 deletions
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18
drivers/block/null_blk.c
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@ -240,19 +240,19 @@ static enum hrtimer_restart null_cmd_timer_expired(struct hrtimer *timer)
while ((entry = llist_del_all(&cq->list)) != NULL) {
entry = llist_reverse_order(entry);
do {
struct request_queue *q = NULL;
cmd = container_of(entry, struct nullb_cmd, ll_list);
entry = entry->next;
if (cmd->rq)
q = cmd->rq->q;
end_cmd(cmd);
if (cmd->rq) {
struct request_queue *q = cmd->rq->q;
if (!q->mq_ops && blk_queue_stopped(q)) {
spin_lock(q->queue_lock);
if (blk_queue_stopped(q))
blk_start_queue(q);
spin_unlock(q->queue_lock);
}
if (q && !q->mq_ops && blk_queue_stopped(q)) {
spin_lock(q->queue_lock);
if (blk_queue_stopped(q))
blk_start_queue(q);
spin_unlock(q->queue_lock);
}
} while (entry);
}