[Mesa-dev] [PATCH] radeon: fixed division by zero

[Nicolai Hähnle]

On 18.05.2016 08:17, Jakob Sinclair wrote:
> In the function r600_test_dma the max_width and max_height can be set to
> zero.

Thanks for looking into that. Can they really? I see

	max_width = MIN2(tsrc.width0, tdst.width0);
	max_height = MIN2(tsrc.height0, tdst.height0);

and

	tsrc.width0 = (rand() % max_tex_side_gen) + 1;

and similarly for tdst.

Given that, I'd prefer instead an assert(max_width > 0 && max_height > 
0) to help Coverity out.

Thanks,
Nicolai

> These variables are later used to do a modulo operation which can
> lead to unexpected behavior if they are zero. This patch corrects that
> by first checking if the max_width or max_height are zero and if they
> are it sets width or height to one. Issue was discoverd by Coverity.
>
> CID: 1361542, 1361543
>
> Signed-off-by: Jakob Sinclair <sinclair.jakob at openmailbox.org>
> ---
>   src/gallium/drivers/radeon/r600_test_dma.c | 11 +++++++++--
>   1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/src/gallium/drivers/radeon/r600_test_dma.c b/src/gallium/drivers/radeon/r600_test_dma.c
> index c203b4d..37d6202 100644
> --- a/src/gallium/drivers/radeon/r600_test_dma.c
> +++ b/src/gallium/drivers/radeon/r600_test_dma.c
> @@ -345,8 +345,15 @@ void r600_test_dma(struct r600_common_screen *rscreen)
>   					dstx = rand() % (tdst.width0 - width + 1) & ~0x7;
>   					dsty = rand() % (tdst.height0 - height + 1) & ~0x7;
>   				} else {
> -					width = (rand() % max_width) + 1;
> -					height = (rand() % max_height) + 1;
> +					if (max_width == 0)
> +						width = 1;
> +					else
> +						width = (rand() % max_width) + 1;
> +
> +					if (max_height == 0)
> +						height = 1;
> +					else
> +						height = (rand() % max_height) + 1;
>
>   					srcx = rand() % (tsrc.width0 - width + 1);
>   					srcy = rand() % (tsrc.height0 - height + 1);
>