From 869c554808ccf7ddd25be5317073b88ceddb8507 Mon Sep 17 00:00:00 2001 From: Adrian Hunter Date: Thu, 25 Aug 2016 14:11:43 -0600 Subject: [PATCH] mmc: fix use-after-free of struct request 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 Tested-by: Hans de Goede Fixes: c2df40dfb8c0 ("drivers: use req op accessor") Signed-off-by: Jens Axboe --- drivers/mmc/card/block.c | 4 ++-- drivers/mmc/card/queue.c | 4 +++- 2 files changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c index 82503e6f04b3..2206d4477dbb 100644 --- a/drivers/mmc/card/block.c +++ b/drivers/mmc/card/block.c @@ -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. diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c index 29578e98603d..708057261b38 100644 --- a/drivers/mmc/card/queue.c +++ b/drivers/mmc/card/queue.c @@ -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;