[PATCH v2] mtd: rawnand: atmel: Fix potential NULL pointer dereference

From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
To: Tudor Ambarus <tudor.ambarus@microchip.com>,
	Boris Brezillon <boris.brezillon@bootlin.com>,
	Miquel Raynal <miquel.raynal@bootlin.com>,
	Richard Weinberger <richard@nod.at>,
	David Woodhouse <dwmw2@infradead.org>,
	Brian Norris <computersforpeace@gmail.com>,
	Marek Vasut <marek.vasut@gmail.com>,
	Nicolas Ferre <nicolas.ferre@microchip.com>,
	Alexandre Belloni <alexandre.belloni@bootlin.com>,
	Ludovic Desroches <ludovic.desroches@microchip.com>
Cc: linux-mtd@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	"Gustavo A. R. Silva" <gustavo@embeddedor.com>
Subject: [PATCH v2] mtd: rawnand: atmel: Fix potential NULL pointer dereference
Date: Tue, 18 Sep 2018 08:55:55 -0500	[thread overview]
Message-ID: <20180918135555.GA18114@embeddedor.com> (raw)

There is a potential execution path in which function
of_find_compatible_node() returns NULL. In such a case,
we end up having a NULL pointer dereference when accessing
pointer *nfc_np* in function of_clk_get().

So, we better don't take any chances and fix this by null
checking pointer *nfc_np* before calling of_clk_get().

Addresses-Coverity-ID: 1473052 ("Dereference null return value")
Fixes: f88fc122cc34 ("mtd: nand: Cleanup/rework the atmel_nand driver")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
Changes in v2:
 - Add Fixes tag to the commit log.
 - Remove blank line before null checking nfc_np.

 drivers/mtd/nand/raw/atmel/nand-controller.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/mtd/nand/raw/atmel/nand-controller.c b/drivers/mtd/nand/raw/atmel/nand-controller.c
index a38633a..5bfbe97 100644
--- a/drivers/mtd/nand/raw/atmel/nand-controller.c
+++ b/drivers/mtd/nand/raw/atmel/nand-controller.c
@@ -2034,6 +2034,10 @@ atmel_hsmc_nand_controller_legacy_init(struct atmel_hsmc_nand_controller *nc)
 	nand_np = dev->of_node;
 	nfc_np = of_find_compatible_node(dev->of_node, NULL,
 					 "atmel,sama5d3-nfc");
+	if (!nfc_np) {
+		dev_err(dev, "Could not find device node for sama5d3-nfc\n");
+		return -ENODEV;
+	}
 
 	nc->clk = of_clk_get(nfc_np, 0);
 	if (IS_ERR(nc->clk)) {
-- 
2.7.4

