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mmc: fix use-after-free of struct request

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We call mmc_req_is_special() after having processed a request, but
it could be freed after that. Check that ahead of time, and use
the cached value.

Reported-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: Hans de Goede <hdegoede@redhat.com>
Fixes: c2df40dfb8 ("drivers: use req op accessor")

Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Adrian Hunter 2016-08-25 14:11:43 -06:00 committed by Jens Axboe
parent f2791e7ead
commit 869c554808
2 changed files with 5 additions and 3 deletions
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4
drivers/mmc/card/block.c
View File

@ -2151,6 +2151,7 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
struct mmc_card *card = md->queue.card;
struct mmc_host *host = card->host;
unsigned long flags;
bool req_is_special = mmc_req_is_special(req);
if (req && !mq->mqrq_prev->req)
/* claim host only for the first request */
@ -2191,8 +2192,7 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
}
out:
if ((!req && !(mq->flags & MMC_QUEUE_NEW_REQUEST)) ||
mmc_req_is_special(req))
if ((!req && !(mq->flags & MMC_QUEUE_NEW_REQUEST)) || req_is_special)
/*
* Release host when there are no more requests
* and after special request(discard, flush) is done.

4
drivers/mmc/card/queue.c
View File

@ -65,6 +65,8 @@ static int mmc_queue_thread(void *d)
spin_unlock_irq(q->queue_lock);
if (req || mq->mqrq_prev->req) {
bool req_is_special = mmc_req_is_special(req);
set_current_state(TASK_RUNNING);
mq->issue_fn(mq, req);
cond_resched();
@ -80,7 +82,7 @@ static int mmc_queue_thread(void *d)
* has been finished. Do not assign it to previous
* request.
*/
if (mmc_req_is_special(req))
if (req_is_special)
mq->mqrq_cur->req = NULL;
mq->mqrq_prev->brq.mrq.data = NULL;