Mar 22 2010

[ARM] pxa: avoid NULL dereferencing in error handling of ssp.c 

Author: Julia Lawall <julia@diku.dk>

The assignments of res to the results of the two calls to
platform_get_resource make it impossible to use res in the error handling
code in the arguments to release_mem_region.

The semantic match that finds the former problem is as follows:
(http://coccinelle.lip6.fr/)

// 
@r exists@
expression E, E1;
identifier f;
statement S1,S3;
iterator iter;
@@

if ((E == NULL && ...) || ...)
{
 ... when != false ((E == NULL && ...) || ...)
     when != true  ((E != NULL && ...) || ...)
     when != iter(E,...) S1
     when != E = E1
(
 sizeof(E->f)
|
* E->f
)
 ... when any
 return ...;
}
else S3
// 

Signed-off-by: Julia Lawall 
Signed-off-by: Eric Miao 

---
 arch/arm/plat-pxa/ssp.c | 32 ++++++++++++++++----------------
 1 file changed, 16 insertions(+), 16 deletions(-)
 
diff --git a/arch/arm/plat-pxa/ssp.c b/arch/arm/plat-pxa/ssp.c
index cfebcd8..3bf704d 100644
--- a/arch/arm/plat-pxa/ssp.c
+++ b/arch/arm/plat-pxa/ssp.c
@@ -92,6 +92,22 @@ static int __devinit ssp_probe(struct platform_device *pdev)
 		goto err_free;
 	}
 
+	res = platform_get_resource(pdev, IORESOURCE_DMA, 0);
+	if (res == NULL) {
+		dev_err(&pdev->dev, "no SSP RX DRCMR defined\n");
+		ret = -ENODEV;
+		goto err_free_clk;
+	}
+	ssp->drcmr_rx = res->start;
+
+	res = platform_get_resource(pdev, IORESOURCE_DMA, 1);
+	if (res == NULL) {
+		dev_err(&pdev->dev, "no SSP TX DRCMR defined\n");
+		ret = -ENODEV;
+		goto err_free_clk;
+	}
+	ssp->drcmr_tx = res->start;
+
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (res == NULL) {
 		dev_err(&pdev->dev, "no memory resource defined\n");
@@ -123,22 +139,6 @@ static int __devinit ssp_probe(struct platform_device *pdev)
 		goto err_free_io;
 	}
 
-	res = platform_get_resource(pdev, IORESOURCE_DMA, 0);
-	if (res == NULL) {
-		dev_err(&pdev->dev, "no SSP RX DRCMR defined\n");
-		ret = -ENODEV;
-		goto err_free_io;
-	}
-	ssp->drcmr_rx = res->start;
-
-	res = platform_get_resource(pdev, IORESOURCE_DMA, 1);
-	if (res == NULL) {
-		dev_err(&pdev->dev, "no SSP TX DRCMR defined\n");
-		ret = -ENODEV;
-		goto err_free_io;
-	}
-	ssp->drcmr_tx = res->start;
-
 	/* PXA2xx/3xx SSP ports starts from 1 and the internal pdev->id
 	 * starts from 0, do a translation here
 	 */

qlambert