Re: [PATCH v3] drm/radeon: fix integer overflow in radeon_align_pitch()

[Alex Deucher]

Applied.  Thanks!

On Wed, Apr 15, 2026 at 6:14 PM Werner Kasselman <werner@xxxxxxxxxx> wrote:
>
> radeon_align_pitch() has the same kind of overflow issue as the old
> amdgpu helper: both the alignment round-up add and the final
> 'aligned * cpp' calculation can overflow signed int.
>
> If that wraps, radeon_mode_dumb_create() can end up returning an
> invalid pitch or creating a zero-sized dumb buffer.
>
> Fix this by using check_add_overflow() for the alignment round-up and
> check_mul_overflow() for the final pitch calculation, returning 0 on
> overflow. Also reject zero pitch and 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>
> ---
> v3:
> - Squash this fix with the earlier zero pitch/size validation change.
> - Use overflow helpers for both the alignment round-up and final
>   pitch calculation.
>
>  drivers/gpu/drm/radeon/radeon_gem.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_gem.c b/drivers/gpu/drm/radeon/radeon_gem.c
> index 20fc87409f2e..8ce180e22d1d 100644
> --- a/drivers/gpu/drm/radeon/radeon_gem.c
> +++ b/drivers/gpu/drm/radeon/radeon_gem.c
> @@ -28,6 +28,7 @@
>
>  #include <linux/debugfs.h>
>  #include <linux/iosys-map.h>
> +#include <linux/overflow.h>
>  #include <linux/pci.h>
>
>  #include <drm/drm_device.h>
> @@ -812,6 +813,7 @@ int radeon_align_pitch(struct radeon_device *rdev, int width, int cpp, bool tile
>         int aligned = width;
>         int align_large = (ASIC_IS_AVIVO(rdev)) || tiled;
>         int pitch_mask = 0;
> +       int pitch;
>
>         switch (cpp) {
>         case 1:
> @@ -826,9 +828,12 @@ int radeon_align_pitch(struct radeon_device *rdev, int width, int cpp, bool tile
>                 break;
>         }
>
> -       aligned += pitch_mask;
> +       if (check_add_overflow(aligned, pitch_mask, &aligned))
> +               return 0;
>         aligned &= ~pitch_mask;
> -       return aligned * cpp;
> +       if (check_mul_overflow(aligned, cpp, &pitch))
> +               return 0;
> +       return pitch;
>  }
>
>  int radeon_mode_dumb_create(struct drm_file *file_priv,
> @@ -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