Re: [PATCH] OMAPDSS: OMAPFB: Fix possible null pointer dereferencing

[Tomi Valkeinen]

On 2012-11-19 07:10, Tushar Behera wrote:
> If display is NULL, display->output would lead to kernel panic.
> 
> Signed-off-by: Tushar Behera <tushar.beh...@linaro.org>
> ---
>  drivers/video/omap2/omapfb/omapfb-ioctl.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/video/omap2/omapfb/omapfb-ioctl.c 
> b/drivers/video/omap2/omapfb/omapfb-ioctl.c
> index 55a39be..532a31b 100644
> --- a/drivers/video/omap2/omapfb/omapfb-ioctl.c
> +++ b/drivers/video/omap2/omapfb/omapfb-ioctl.c
> @@ -787,7 +787,7 @@ int omapfb_ioctl(struct fb_info *fbi, unsigned int cmd, 
> unsigned long arg)
>  
>       case OMAPFB_WAITFORVSYNC:
>               DBG("ioctl WAITFORVSYNC\n");
> -             if (!display && !display->output && !display->output->manager) {
> +             if (!display || !display->output || !display->output->manager) {
>                       r = -EINVAL;
>                       break;
>               }
> 

Thanks, good catch. However, the patch description is not very good.
If you agree with the change, I'll apply the patch with the description:


OMAPFB: Fix possible null pointer dereferencing                          
                                                                         
Commit 952cbaaa9b8beacc425f9aedf370468cbb737a2c (OMAPFB: Change          
dssdev->manager references) added checks for OMAPFB_WAITFORVSYNC ioctl   
to verify that the display, output and overlay manager exist. However,   
the code erroneously uses && for each part, which means that             
OMAPFB_WAITFORVSYNC may crash the kernel if no display, output or        
manager is associated with the framebuffer.                              
                                                                         
This patch fixes the issue by using ||.                                  


 Tomi

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