2009-10-17 06:42:48

by Julia Lawall

Subject: [PATCH 13/14] arch/arm/plat-s3c24xx: Move dereference after NULL test

From: Julia Lawall <[email protected]>

If the NULL test on buf is needed, then the dereference should be after the
NULL test.

A simplified version of the semantic match that detects this problem is as
follows (http://coccinelle.lip6.fr/):

// <smpl>
@match exists@
expression x, E;
identifier fld;
@@

* x->fld
... when != \(x = E\|&x\)
* x == NULL
// </smpl>

Signed-off-by: Julia Lawall <[email protected]>

---
arch/arm/plat-s3c24xx/dma.c | 6 +++---
1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/arm/plat-s3c24xx/dma.c b/arch/arm/plat-s3c24xx/dma.c
index 196b191..f046f8c 100644
--- a/arch/arm/plat-s3c24xx/dma.c
+++ b/arch/arm/plat-s3c24xx/dma.c
@@ -208,14 +208,14 @@ s3c2410_dma_loadbuffer(struct s3c2410_dma_chan *chan,
{
unsigned long reload;

- pr_debug("s3c2410_chan_loadbuffer: loading buff %p (0x%08lx,0x%06x)\n",
- buf, (unsigned long)buf->data, buf->size);
-
if (buf == NULL) {
dmawarn("buffer is NULL\n");
return -EINVAL;
}

+ pr_debug("s3c2410_chan_loadbuffer: loading buff %p (0x%08lx,0x%06x)\n",
+ buf, (unsigned long)buf->data, buf->size);
+
/* check the state of the channel before we do anything */

if (chan->load_state == S3C2410_DMALOAD_1LOADED) {

2009-10-19 11:26:26

by Ben Dooks

Subject: Re: [PATCH 13/14] arch/arm/plat-s3c24xx: Move dereference after NULL test

On Sat, Oct 17, 2009 at 08:42:49AM +0200, Julia Lawall wrote:
> From: Julia Lawall <[email protected]>
>
> If the NULL test on buf is needed, then the dereference should be after the
> NULL test.
>
> A simplified version of the semantic match that detects this problem is as
> follows (http://coccinelle.lip6.fr/):
>
> // <smpl>
> @match exists@
> expression x, E;
> identifier fld;
> @@
>
> * x->fld
> ... when != \(x = E\|&x\)
> * x == NULL
> // </smpl>
>
> Signed-off-by: Julia Lawall <[email protected]>

I'll apply it to next-s3c24xx-fixes unless someone else wants to
pick it up for inclusion.

> ---
> arch/arm/plat-s3c24xx/dma.c | 6 +++---
> 1 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm/plat-s3c24xx/dma.c b/arch/arm/plat-s3c24xx/dma.c
> index 196b191..f046f8c 100644
> --- a/arch/arm/plat-s3c24xx/dma.c
> +++ b/arch/arm/plat-s3c24xx/dma.c
> @@ -208,14 +208,14 @@ s3c2410_dma_loadbuffer(struct s3c2410_dma_chan *chan,
> {
> unsigned long reload;
>
> - pr_debug("s3c2410_chan_loadbuffer: loading buff %p (0x%08lx,0x%06x)\n",
> - buf, (unsigned long)buf->data, buf->size);
> -
> if (buf == NULL) {
> dmawarn("buffer is NULL\n");
> return -EINVAL;
> }
>
> + pr_debug("s3c2410_chan_loadbuffer: loading buff %p (0x%08lx,0x%06x)\n",
> + buf, (unsigned long)buf->data, buf->size);
> +
> /* check the state of the channel before we do anything */
>
> if (chan->load_state == S3C2410_DMALOAD_1LOADED) {
> --
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--
Ben ([email protected], http://www.fluff.org/)

'a smiley only costs 4 bytes'