From patchwork Thu May 25 17:04:55 2017
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Subject: [v2] mmc: bcm2835: fix potential null pointer dereferences
From: "Gustavo A. R. Silva" <garsilva@embeddedor.com>
X-Patchwork-Id: 9748761
Message-Id: <20170525170455.GA6904@embeddedgus>
To: Stefan Wahren <stefan.wahren@i2se.com>,
 Ulf Hansson <ulf.hansson@linaro.org>,
 Florian Fainelli <f.fainelli@gmail.com>,
 Ray Jui <rjui@broadcom.com>, Scott Branden <sbranden@broadcom.com>,
 bcm-kernel-feedback-list@broadcom.com, Eric Anholt <eric@anholt.net>
Cc: "Gustavo A. R. Silva" <garsilva@embeddedor.com>,
 linux-mmc@vger.kernel.org, linux-rpi-kernel@lists.infradead.org,
 linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Date: Thu, 25 May 2017 12:04:55 -0500

Null check at line 1165: if (mrq->cmd), implies that mrq->cmd might
be NULL.
Add null checks before dereferencing pointer mrq->cmd in order to avoid
any potential NULL pointer dereference.

Addresses-Coverity-ID: 1408740
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
---
Changes in v2:
 Change subject to make it clear the patch is bcm2835 related.

 drivers/mmc/host/bcm2835.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/host/bcm2835.c b/drivers/mmc/host/bcm2835.c
index 1f343a4..abba9a2 100644
--- a/drivers/mmc/host/bcm2835.c
+++ b/drivers/mmc/host/bcm2835.c
@@ -1172,7 +1172,10 @@ static void bcm2835_request(struct mmc_host *mmc, struct mmc_request *mrq)
 	if (mrq->data && !is_power_of_2(mrq->data->blksz)) {
 		dev_err(dev, "unsupported block size (%d bytes)\n",
 			mrq->data->blksz);
-		mrq->cmd->error = -EINVAL;
+
+		if (mrq->cmd)
+			mrq->cmd->error = -EINVAL;
+
 		mmc_request_done(mmc, mrq);
 		return;
 	}
@@ -1194,7 +1197,10 @@ static void bcm2835_request(struct mmc_host *mmc, struct mmc_request *mrq)
 			readl(host->ioaddr + SDCMD) & SDCMD_CMD_MASK,
 			edm);
 		bcm2835_dumpregs(host);
-		mrq->cmd->error = -EILSEQ;
+
+		if (mrq->cmd)
+			mrq->cmd->error = -EILSEQ;
+
 		bcm2835_finish_request(host);
 		mutex_unlock(&host->mutex);
 		return;
@@ -1207,7 +1213,7 @@ static void bcm2835_request(struct mmc_host *mmc, struct mmc_request *mrq)
 			if (!host->use_busy)
 				bcm2835_finish_command(host);
 		}
-	} else if (bcm2835_send_command(host, mrq->cmd)) {
+	} else if (mrq->cmd && bcm2835_send_command(host, mrq->cmd)) {
 		if (host->data && host->dma_desc) {
 			/* DMA transfer starts now, PIO starts after irq */
 			bcm2835_start_dma(host);