mmc: sdhci: Check mrq->cmd in sdhci_tasklet_finish

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>
Cc: <stable@kernel.org>
Signed-off-by: Chris Ball <cjb@laptop.org>

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 9e15f41..fd8f488 100644 (file)
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1345,7 +1345,7 @@ 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))) {