[34-longterm 108/196] mmc: sdhci: Check mrq->cmd in sdhci_tasklet_finish

[Paul Gortmaker]

From: Ben Dooks <ben-linux@xxxxxxxxx>

                   -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    If you see a problem with using this for longterm, please comment.
                   -------------------

commit b7b4d3426d2b5ecab21578eb20d8e456a1aace8f upstream.

It seems that under certain circumstances that the sdhci_tasklet_finish()
call can be entered with mrq->cmd set to NULL, causing the system to crash
with a NULL pointer de-reference.

Unable to handle kernel NULL pointer dereference at virtual address 00000000
PC is at sdhci_tasklet_finish+0x34/0xe8
LR is at sdhci_tasklet_finish+0x24/0xe8

Seen on S3C6410 system.

Signed-off-by: Ben Dooks <ben-linux@xxxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Chris Ball <cjb@xxxxxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
 drivers/mmc/host/sdhci.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 9d4fdfa..6441e22 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1279,7 +1279,7 @@ static void sdhci_tasklet_finish(unsigned long param)
 	 * upon error conditions.
 	 */
 	if (!(host->flags & SDHCI_DEVICE_DEAD) &&
-		(mrq->cmd->error ||
+	    ((mrq->cmd && mrq->cmd->error) ||
 		 (mrq->data && (mrq->data->error ||
 		  (mrq->data->stop && mrq->data->stop->error))) ||
 		   (host->quirks & SDHCI_QUIRK_RESET_AFTER_REQUEST))) {
-- 
1.7.9.3

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