[PATCH] [22/98] mmc: sdhci: Check mrq->cmd in sdhci_tasklet_finish

Andi Kleen
2011-07-27T00:35:23Z

From: Ben Dooks <ben-linux@fluff.org>

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@fluff.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

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

Index: linux-2.6.35.y/drivers/mmc/host/sdhci.c
===================================================================
--- linux-2.6.35.y.orig/drivers/mmc/host/sdhci.c
+++ linux-2.6.35.y/drivers/mmc/host/sdhci.c
@@ -1289,7 +1289,7 @@ static void sdhci_tasklet_finish(unsigne
* 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))) {