linux-kernel - [PATCH v3] i2c: busses/i2c-pxa.c: fix potential null pointer dereference error

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Message-ID: <20130214112818.GA18774@gmail.com>
Date:	Thu, 14 Feb 2013 12:28:18 +0100
From:	Cong Ding <dinggnu@...il.com>
To:	Haojian Zhuang <haojian.zhuang@...il.com>
Cc:	Kyungmin Park <kmpark@...radead.org>,
	Wolfram Sang <w.sang@...gutronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Karol Lewandowski <k.lewandowsk@...sung.com>,
	Haojian Zhuang <haojian.zhuang@...vell.com>,
	linux-i2c@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [PATCH v3] i2c: busses/i2c-pxa.c: fix potential null pointer
 dereference error

If it goes to eclk through line 1107, the variable res would be NULL. It will
cause a null pointer dereference error if we call release_mem_region. The
correct way should be using devm_kzalloc rather than kzalloc to allocate
memory.

Signed-off-by: Cong Ding <dinggnu@...il.com>
---
 drivers/i2c/busses/i2c-pxa.c |   22 ++++++++--------------
 1 file changed, 8 insertions(+), 14 deletions(-)

diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
index 1034d93..dd2d640 100644
--- a/drivers/i2c/busses/i2c-pxa.c
+++ b/drivers/i2c/busses/i2c-pxa.c
@@ -1094,29 +1094,23 @@ static int i2c_pxa_probe(struct platform_device *dev)
 	struct resource *res = NULL;
 	int ret, irq;
 
-	i2c = kzalloc(sizeof(struct pxa_i2c), GFP_KERNEL);
-	if (!i2c) {
-		ret = -ENOMEM;
-		goto emalloc;
-	}
+	i2c = devm_kzalloc(sizeof(struct pxa_i2c), GFP_KERNEL);
+	if (!i2c)
+		return -ENOMEM;
 
 	ret = i2c_pxa_probe_dt(dev, i2c, &i2c_type);
 	if (ret > 0)
 		ret = i2c_pxa_probe_pdata(dev, i2c, &i2c_type);
 	if (ret < 0)
-		goto eclk;
+		return ret;
 
 	res = platform_get_resource(dev, IORESOURCE_MEM, 0);
 	irq = platform_get_irq(dev, 0);
-	if (res == NULL || irq < 0) {
-		ret = -ENODEV;
-		goto eclk;
-	}
+	if (res == NULL || irq < 0)
+		return -ENODEV;
 
-	if (!request_mem_region(res->start, resource_size(res), res->name)) {
-		ret = -ENOMEM;
-		goto eclk;
-	}
+	if (!request_mem_region(res->start, resource_size(res), res->name))
+		return -ENOMEM;
 
 	i2c->adap.owner   = THIS_MODULE;
 	i2c->adap.retries = 5;
-- 
1.7.9.5

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