Re: [PATCH] arch/arm/mach-pxa: avoid NULL dereference in error handling code

[Eric Miao]

On Mon, Mar 22, 2010 at 4:48 AM, Julia Lawall <julia@xxxxxxx> wrote:
> From: Julia Lawall <julia@xxxxxxx>
>
> 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.
>

Nice catch, I've yet made a small change to move the block of getting
dma resource earlier so to avoid introducing another variable pres.

> At the same time, code of the form res->end - res->start + 1 is converted
> to use resource_size.
>

OK, I've separated this into an individual patch with the above one,
rebased against my 'ssp_cleanup' branch as follows (note: the ssp.c
has been moved to plat-pxa for code sharing):

=====================================================
commit 97be6e52dc0aabaea07222bd0486e3b2df3e1baa
Author: Julia Lawall <julia@xxxxxxx>
Date:   Mon Mar 22 16:11:55 2010 +0800

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

    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/)

    // <smpl>
    @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
    // </smpl>

    Signed-off-by: Julia Lawall <julia@xxxxxxx>
    Signed-off-by: Eric Miao <eric.y.miao@xxxxxxxxx>

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
 	 */

===============================================================================

commit 00921f0d5f21f213b8407d348b53fdce4ad383bd
Author: Julia Lawall <julia@xxxxxxx>
Date:   Mon Mar 22 16:16:24 2010 +0800

    [ARM] pxa: use resource_size() in ssp.c

    Signed-off-by: Julia Lawall <julia@xxxxxxx>
    Signed-off-by: Eric Miao <eric.y.miao@xxxxxxxxx>

diff --git a/arch/arm/plat-pxa/ssp.c b/arch/arm/plat-pxa/ssp.c
index 3bf704d..52c07cc 100644
--- a/arch/arm/plat-pxa/ssp.c
+++ b/arch/arm/plat-pxa/ssp.c
@@ -115,7 +115,7 @@ static int __devinit ssp_probe(struct platform_device *pdev)
 		goto err_free_clk;
 	}

-	res = request_mem_region(res->start, res->end - res->start + 1,
+	res = request_mem_region(res->start, resource_size(res),
 			pdev->name);
 	if (res == NULL) {
 		dev_err(&pdev->dev, "failed to request memory resource\n");
@@ -125,7 +125,7 @@ static int __devinit ssp_probe(struct platform_device *pdev)

 	ssp->phys_base = res->start;

-	ssp->mmio_base = ioremap(res->start, res->end - res->start + 1);
+	ssp->mmio_base = ioremap(res->start, resource_size(res));
 	if (ssp->mmio_base == NULL) {
 		dev_err(&pdev->dev, "failed to ioremap() registers\n");
 		ret = -ENODEV;
@@ -156,7 +156,7 @@ static int __devinit ssp_probe(struct platform_device *pdev)
 err_free_io:
 	iounmap(ssp->mmio_base);
 err_free_mem:
-	release_mem_region(res->start, res->end - res->start + 1);
+	release_mem_region(res->start, resource_size(res));
 err_free_clk:
 	clk_put(ssp->clk);
 err_free:
@@ -176,7 +176,7 @@ static int __devexit ssp_remove(struct
platform_device *pdev)
 	iounmap(ssp->mmio_base);

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	release_mem_region(res->start, res->end - res->start + 1);
+	release_mem_region(res->start, resource_size(res));

 	clk_put(ssp->clk);
--
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