Re: [PATCH 2/2] drm/radeon: fix integer overflow in radeon_align_pitch()

[Alex Deucher]

On Tue, Apr 7, 2026 at 3:41 AM Werner Kasselman <werner@xxxxxxxxxx> wrote:
>
> radeon_align_pitch() has the same integer overflow as amdgpu's variant:
> 'aligned * cpp' can overflow signed int to 0 when alignment rounding
> pushes the width past INT_MAX/cpp. This produces a 0-byte GEM buffer
> via radeon_mode_dumb_create(), reachable from unprivileged userspace
> via DRM_IOCTL_MODE_CREATE_DUMB on the render node.
>
> Add an overflow check in radeon_align_pitch() and reject zero pitch/size
> in radeon_mode_dumb_create().
>
> Found via AST-based call-graph analysis using sqry.
>
> Fixes: ff72145badb8 ("drm: dumb scanout create/mmap for intel/radeon (v3)")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Werner Kasselman <werner@xxxxxxxxxxx>

Can you fix this up similar to the amdgpu patch?

Thanks,

Alex

> ---
>  drivers/gpu/drm/radeon/radeon_gem.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_gem.c b/drivers/gpu/drm/radeon/radeon_gem.c
> index 20fc87409f2e..2cd179fef347 100644
> --- a/drivers/gpu/drm/radeon/radeon_gem.c
> +++ b/drivers/gpu/drm/radeon/radeon_gem.c
> @@ -828,6 +828,11 @@ int radeon_align_pitch(struct radeon_device *rdev, int width, int cpp, bool tile
>
>         aligned += pitch_mask;
>         aligned &= ~pitch_mask;
> +
> +       /* Guard against integer overflow in aligned * cpp. */
> +       if (aligned > INT_MAX / (cpp ? cpp : 1) || aligned <= 0)
> +               return 0;
> +
>         return aligned * cpp;
>  }
>
> @@ -842,8 +847,12 @@ int radeon_mode_dumb_create(struct drm_file *file_priv,
>
>         args->pitch = radeon_align_pitch(rdev, args->width,
>                                          DIV_ROUND_UP(args->bpp, 8), 0);
> +       if (!args->pitch)
> +               return -EINVAL;
>         args->size = (u64)args->pitch * args->height;
>         args->size = ALIGN(args->size, PAGE_SIZE);
> +       if (!args->size)
> +               return -EINVAL;
>
>         r = radeon_gem_object_create(rdev, args->size, 0,
>                                      RADEON_GEM_DOMAIN_VRAM, 0,
> --
> 2.43.0
>