Re: [Linux-fbdev-devel] [PATCH] drivers/video: Bad error test beforea dereference

From: Nicolas Ferre
Date: Thu Nov 13 2008 - 03:27:09 EST


Hi Andrew,

Nicolas Ferre :
Julien Brunel :
The error test that follows the call to backlight_device_register
semms not to concern the right variable.

A simplified version of the semantic match that finds this problem is
as follows: (http://www.emn.fr/x-info/coccinelle/)
// <smpl>
@def0@
expression x;
position p0;
@@
x@p0 = backlight_device_register(...)

@protected@
expression def0.x,E;
position def0.p0;
position p;
statement S;
@@
x@p0
... when != x = E
if (!IS_ERR(x) && ...) {<... x@p ...>} else S

@unprotected@
expression def0.x;
identifier fld;
position def0.p0;
position p != protected.p;
@@
x@p0
... when != x = E
* x@p->fld
// </smpl>

Signed-off-by: Julien Brunel <brunel@xxxxxxx>
Signed-off-by: Julia Lawall <julia@xxxxxxx>

Acked-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>

I do not know if you noticed this little patch but
I think it will be good if we can queue it for -final.

Do you want me to reformulate the submission or the
original email ok for you ?

---
drivers/video/atmel_lcdfb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff -u -p a/drivers/video/atmel_lcdfb.c b/drivers/video/atmel_lcdfb.c
--- a/drivers/video/atmel_lcdfb.c
+++ b/drivers/video/atmel_lcdfb.c
@@ -132,7 +132,7 @@ static void init_backlight(struct atmel_
bl = backlight_device_register("backlight", &sinfo->pdev->dev,
sinfo, &atmel_lcdc_bl_ops);
- if (IS_ERR(sinfo->backlight)) {
+ if (IS_ERR(bl)) {
dev_err(&sinfo->pdev->dev, "error %ld on backlight register\n",
PTR_ERR(bl));
return;

Thanks, regards,
--
Nicolas Ferre

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/