It is possible for queuedata to be cleared in mmc_cleanup_queue before the request has been started. This will result in dereferencing a null pointer. Signed-off-by: Raul E Rangel <rrangel@xxxxxxxxxxxx> --- I think we should cherry-pick 41e3efd07d5a02c80f503e29d755aa1bbb4245de https://lore.kernel.org/patchwork/patch/856512/ into 4.14. It fixes a potential resource leak when shutting down the request queue. Once this patch is applied, there is a potential for a null pointer dereference. That's what this patch fixes. The next patch is just an optimization to stop processing earlier. See https://patchwork.kernel.org/patch/10925469/ for the initial motivation. This commit applies to v4.14.116. This doesn't apply to 5.1 since mmc has been migrated to blk-mq. Thanks, Raul drivers/mmc/core/queue.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c index 0a4e77a5ba33..4bf1a9c6440b 100644 --- a/drivers/mmc/core/queue.c +++ b/drivers/mmc/core/queue.c @@ -159,8 +159,14 @@ static int mmc_init_request(struct request_queue *q, struct request *req, { struct mmc_queue_req *mq_rq = req_to_mmc_queue_req(req); struct mmc_queue *mq = q->queuedata; - struct mmc_card *card = mq->card; - struct mmc_host *host = card->host; + struct mmc_card *card; + struct mmc_host *host; + + if (!mq) + return -ENODEV; + + card = mq->card; + host = card->host; mq_rq->sg = mmc_alloc_sg(host->max_segs, gfp); if (!mq_rq->sg) -- 2.21.0.1020.gf2820cf01a-goog
