[patch] drm/radeon: integer underflow in radeon_cp_dispatch_texture()

[Alex Deucher]

On Tue, Dec 23, 2014 at 4:56 AM, Dan Carpenter <dan.carpenter at oracle.com> wrote:
> The test:
>
>         if (size > RADEON_MAX_TEXTURE_SIZE) {
>
> "size" is an integer and it's controled by the user so it can be
> negative and the test can underflow.  Later we use "size" in:
>
>         dwords = size / 4;
>         ...
>         RADEON_COPY_MT(buffer, data, (int)(dwords * sizeof(u32)));
>
> It causes memory corruption to copy a negative size buffer.
>
> Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>

Applied to my fixes tree.  thanks!

Alex

> ---
> Static checkers complain about the integer overflows here, and there are
> many real overflows but they appear harmless.
>
> diff --git a/drivers/gpu/drm/radeon/radeon_state.c b/drivers/gpu/drm/radeon/radeon_state.c
> index 535403e..15aee72 100644
> --- a/drivers/gpu/drm/radeon/radeon_state.c
> +++ b/drivers/gpu/drm/radeon/radeon_state.c
> @@ -1703,7 +1703,7 @@ static int radeon_cp_dispatch_texture(struct drm_device * dev,
>         u32 format;
>         u32 *buffer;
>         const u8 __user *data;
> -       int size, dwords, tex_width, blit_width, spitch;
> +       unsigned int size, dwords, tex_width, blit_width, spitch;
>         u32 height;
>         int i;
>         u32 texpitch, microtile;
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