linux-kernel - [stable/4.14.y PATCH 2/3] mmc: Fix null pointer dereference in mmc_init

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Message-Id: <20190513175521.84955-3-rrangel@chromium.org>
Date:   Mon, 13 May 2019 11:55:20 -0600
From:   Raul E Rangel <rrangel@...omium.org>
To:     stable@...r.kernel.org
Cc:     linux-mmc@...r.kernel.org, djkurtz@...gle.com,
        adrian.hunter@...el.com, zwisler@...omium.org,
        Raul E Rangel <rrangel@...omium.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-kernel@...r.kernel.org, Ulf Hansson <ulf.hansson@...aro.org>
Subject: [stable/4.14.y PATCH 2/3] mmc: Fix null pointer dereference in mmc_init_request

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@...omium.org>
---

 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 d99fa4e63033c..bd7d521d5ad9d 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