[PATCH] mci: dove: fix dereference of nullable pointer

[PATCH] mci: dove: fix dereference of nullable pointer

[Ahmad Fatoum]

data->{blocks, blocksize, flags} are all used outside of the if clause
checking whether data is not NULL.
Fix this to avoid dereferencing null pointers.

Fixes: bdcf89d274 ("mci: add Marvell Dove SDHCI driver")
Cc: Michael Grzeschik <m.grzeschik@pengutronix.de>
Signed-off-by: Ahmad Fatoum <ahmad@a3f.at>
---
 drivers/mci/dove-sdhci.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/mci/dove-sdhci.c b/drivers/mci/dove-sdhci.c
index e71a27ce4f33..bccda5399491 100644
--- a/drivers/mci/dove-sdhci.c
+++ b/drivers/mci/dove-sdhci.c
@@ -116,7 +116,7 @@ static int dove_sdhci_mci_send_cmd(struct mci_host *mci, struct mci_cmd *cmd,
 	u32 command, xfer;
 	u64 start;
 	int ret;
-	unsigned int num_bytes = data->blocks * data->blocksize;
+	unsigned int num_bytes = 0;
 	struct dove_sdhci *host = priv_from_mci_host(mci);
 
 	sdhci_write32(&host->sdhci, SDHCI_INT_STATUS, ~0);
@@ -140,6 +140,7 @@ static int dove_sdhci_mci_send_cmd(struct mci_host *mci, struct mci_cmd *cmd,
 
 	/* setup transfer data */
 	if (data) {
+		num_bytes = data->blocks * data->blocksize;
 		if (data->flags & MMC_DATA_READ)
 			sdhci_write32(&host->sdhci, SDHCI_DMA_ADDRESS, (u32)data->dest);
 		else
@@ -178,14 +179,14 @@ static int dove_sdhci_mci_send_cmd(struct mci_host *mci, struct mci_cmd *cmd,
 
 	sdhci_read_response(&host->sdhci, cmd);
 
-	if (data->flags & MMC_DATA_WRITE)
-		dma_sync_single_for_cpu((unsigned long)data->src,
-					 num_bytes, DMA_TO_DEVICE);
-	else
-		dma_sync_single_for_cpu((unsigned long)data->dest,
+	if (data) {
+		if (data->flags & MMC_DATA_WRITE)
+			dma_sync_single_for_cpu((unsigned long)data->src,
+						num_bytes, DMA_TO_DEVICE);
+		else
+			dma_sync_single_for_cpu((unsigned long)data->dest,
 					 num_bytes, DMA_FROM_DEVICE);
 
-	if (data) {
 		ret = dove_sdhci_wait_for_done(host, SDHCI_INT_XFER_COMPLETE);
 		if (ret) {
 			dev_err(host->mci.hw_dev, "error while transfering data for command %d\n",
-- 
2.20.1


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Re: [PATCH] mci: dove: fix dereference of nullable pointer

[Sascha Hauer]

On Wed, Nov 20, 2019 at 08:38:16AM +0100, Ahmad Fatoum wrote:
> data->{blocks, blocksize, flags} are all used outside of the if clause
> checking whether data is not NULL.
> Fix this to avoid dereferencing null pointers.
> 
> Fixes: bdcf89d274 ("mci: add Marvell Dove SDHCI driver")
> Cc: Michael Grzeschik <m.grzeschik@pengutronix.de>
> Signed-off-by: Ahmad Fatoum <ahmad@a3f.at>
> ---
>  drivers/mci/dove-sdhci.c | 15 ++++++++-------
>  1 file changed, 8 insertions(+), 7 deletions(-)

Applied, thanks

Sascha

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