[PATCH 4.20 71/88] mmc: core: Fix NULL ptr crash from mmc_should_fail_request

[Greg Kroah-Hartman]

4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ritesh Harjani <riteshh@xxxxxxxxxxxxxx>

commit e5723f95d6b493dd437f1199cacb41459713b32f upstream.

In case of CQHCI, mrq->cmd may be NULL for data requests (non DCMD).
In such case mmc_should_fail_request is directly dereferencing
mrq->cmd while cmd is NULL.
Fix this by checking for mrq->cmd pointer.

Fixes: 72a5af554df8 ("mmc: core: Add support for handling CQE requests")
Signed-off-by: Ritesh Harjani <riteshh@xxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/mmc/core/core.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -95,7 +95,7 @@ static void mmc_should_fail_request(stru
 	if (!data)
 		return;
 
-	if (cmd->error || data->error ||
+	if ((cmd && cmd->error) || data->error ||
 	    !should_fail(&host->fail_mmc_request, data->blksz * data->blocks))
 		return;