[v2] media: davinci vpbe: array underflow in vpbe_enum_outputs()

  In vpbe_enum_outputs() we check if (temp_index >= cfg->num_outputs) but
the problem is that temp_index can be negative.  I've made
cgf->num_outputs unsigned to fix this issue.

Fixes: 66715cdc3224 ("[media] davinci vpbe: VPBE display driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
v2: fix it a different way
  

On 25/05/18 15:12, Dan Carpenter wrote:
> In vpbe_enum_outputs() we check if (temp_index >= cfg->num_outputs) but
> the problem is that temp_index can be negative.  I've made
> cgf->num_outputs unsigned to fix this issue.

Shouldn't temp_index also be made unsigned? It certainly would make a lot of
sense to do that.

Regards,

	Hans

> 
> Fixes: 66715cdc3224 ("[media] davinci vpbe: VPBE display driver")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> v2: fix it a different way
> 
> diff --git a/include/media/davinci/vpbe.h b/include/media/davinci/vpbe.h
> index 79a566d7defd..180a05e91497 100644
> --- a/include/media/davinci/vpbe.h
> +++ b/include/media/davinci/vpbe.h
> @@ -92,7 +92,7 @@ struct vpbe_config {
>  	struct encoder_config_info *ext_encoders;
>  	/* amplifier information goes here */
>  	struct amp_config_info *amp;
> -	int num_outputs;
> +	unsigned int num_outputs;
>  	/* Order is venc outputs followed by LCD and then external encoders */
>  	struct vpbe_output *outputs;
>  };
>
  

On Fri, May 25, 2018 at 03:16:21PM +0200, Hans Verkuil wrote:
> On 25/05/18 15:12, Dan Carpenter wrote:
> > In vpbe_enum_outputs() we check if (temp_index >= cfg->num_outputs) but
> > the problem is that temp_index can be negative.  I've made
> > cgf->num_outputs unsigned to fix this issue.
> 
> Shouldn't temp_index also be made unsigned? It certainly would make a lot of
> sense to do that.

Yeah, sure.  It doesn't make any difference in terms of runtime but it's
probably cleaner.

regards,
dan carpenter
  

On Mon, May 28, 2018 at 7:26 AM, Dan Carpenter <dan.carpenter@oracle.com> wrote:
> In vpbe_enum_outputs() we check if (temp_index >= cfg->num_outputs) but
> the problem is that temp_index can be negative.  I've changed the types
> to unsigned to fix this issue.
>
> Fixes: 66715cdc3224 ("[media] davinci vpbe: VPBE display driver")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> v2: fix it a different way
> v3: change everything to unsigned because that's the right thing to do
>     and looks nicer.
>

Acked-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>

Regards,
--Prabhakar Lad

> diff --git a/include/media/davinci/vpbe.h b/include/media/davinci/vpbe.h
> index 79a566d7defd..180a05e91497 100644
> --- a/include/media/davinci/vpbe.h
> +++ b/include/media/davinci/vpbe.h
> @@ -92,7 +92,7 @@ struct vpbe_config {
>         struct encoder_config_info *ext_encoders;
>         /* amplifier information goes here */
>         struct amp_config_info *amp;
> -       int num_outputs;
> +       unsigned int num_outputs;
>         /* Order is venc outputs followed by LCD and then external encoders */
>         struct vpbe_output *outputs;
>  };
> diff --git a/drivers/media/platform/davinci/vpbe.c b/drivers/media/platform/davinci/vpbe.c
> index 18c035ef84cf..c6fee53bff4d 100644
> --- a/drivers/media/platform/davinci/vpbe.c
> +++ b/drivers/media/platform/davinci/vpbe.c
> @@ -126,7 +126,7 @@ static int vpbe_enum_outputs(struct vpbe_device *vpbe_dev,
>                              struct v4l2_output *output)
>  {
>         struct vpbe_config *cfg = vpbe_dev->cfg;
> -       int temp_index = output->index;
> +       unsigned int temp_index = output->index;
>
>         if (temp_index >= cfg->num_outputs)
>                 return -EINVAL;