[PATCH] drivers/video: Bad error test before a dereference

[PATCH] drivers/video: Bad error test before a dereference

[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@diku.dk>
Signed-off-by: Julia Lawall <julia@diku.dk>

---
 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;

Re: [PATCH] drivers/video: Bad error test before a dereference

[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@diku.dk>
> Signed-off-by: Julia Lawall <julia@diku.dk>

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

> 
> ---
>  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

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

[Nicolas Ferre]

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@diku.dk>
>> Signed-off-by: Julia Lawall <julia@diku.dk>
> 
> Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>

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