[PATCH] drm/xe/display: fix potential overflow when multiplying 2 u32

[Murthy, Arun R]

Any comments?

Thanks and Regards,
Arun R Murthy
--------------------

> -----Original Message-----
> From: Murthy, Arun R <arun.r.murthy at intel.com>
> Sent: Monday, March 18, 2024 4:31 PM
> To: intel-gfx at lists.freedesktop.org; intel-xe at lists.freedesktop.org
> Cc: Murthy, Arun R <arun.r.murthy at intel.com>
> Subject: [PATCH] drm/xe/display: fix potential overflow when multiplying 2 u32
> 
> Multiplying XE_PAGE_SIZE with another u32 and the product stored in
> u64 can potentially lead to overflow, use mul_u32_u32 instead.
> 
> Signed-off-by: Arun R Murthy <arun.r.murthy at intel.com>
> ---
>  drivers/gpu/drm/xe/display/xe_fb_pin.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/display/xe_fb_pin.c
> b/drivers/gpu/drm/xe/display/xe_fb_pin.c
> index 722c84a56607..e0b511ff7eab 100644
> --- a/drivers/gpu/drm/xe/display/xe_fb_pin.c
> +++ b/drivers/gpu/drm/xe/display/xe_fb_pin.c
> @@ -29,7 +29,7 @@ write_dpt_rotated(struct xe_bo *bo, struct iosys_map
> *map, u32 *dpt_ofs, u32 bo_
>  		u32 src_idx = src_stride * (height - 1) + column + bo_ofs;
> 
>  		for (row = 0; row < height; row++) {
> -			u64 pte = ggtt->pt_ops->pte_encode_bo(bo, src_idx *
> XE_PAGE_SIZE,
> +			u64 pte = ggtt->pt_ops->pte_encode_bo(bo,
> mul_u32_u32(src_idx,
> +XE_PAGE_SIZE),
>  							      xe-
> >pat.idx[XE_CACHE_WB]);
> 
>  			iosys_map_wr(map, *dpt_ofs, u64, pte); @@ -61,7
> +61,7 @@ write_dpt_remapped(struct xe_bo *bo, struct iosys_map *map, u32
> *dpt_ofs,
> 
>  		for (column = 0; column < width; column++) {
>  			iosys_map_wr(map, *dpt_ofs, u64,
> -				     pte_encode_bo(bo, src_idx * XE_PAGE_SIZE,
> +				     pte_encode_bo(bo, mul_u32_u32(src_idx,
> XE_PAGE_SIZE),
>  				     xe->pat.idx[XE_CACHE_WB]));
> 
>  			*dpt_ofs += 8;
> @@ -118,7 +118,7 @@ static int __xe_pin_fb_vma_dpt(struct
> intel_framebuffer *fb,
>  		u32 x;
> 
>  		for (x = 0; x < size / XE_PAGE_SIZE; x++) {
> -			u64 pte = ggtt->pt_ops->pte_encode_bo(bo, x *
> XE_PAGE_SIZE,
> +			u64 pte = ggtt->pt_ops->pte_encode_bo(bo,
> mul_u32_u32(x,
> +XE_PAGE_SIZE),
>  							      xe-
> >pat.idx[XE_CACHE_WB]);
> 
>  			iosys_map_wr(&dpt->vmap, x * 8, u64, pte); @@ -
> 164,7 +164,7 @@ write_ggtt_rotated(struct xe_bo *bo, struct xe_ggtt *ggtt,
> u32 *ggtt_ofs, u32 bo
>  		u32 src_idx = src_stride * (height - 1) + column + bo_ofs;
> 
>  		for (row = 0; row < height; row++) {
> -			u64 pte = ggtt->pt_ops->pte_encode_bo(bo, src_idx *
> XE_PAGE_SIZE,
> +			u64 pte = ggtt->pt_ops->pte_encode_bo(bo,
> mul_u32_u32(src_idx,
> +XE_PAGE_SIZE),
>  							      xe-
> >pat.idx[XE_CACHE_WB]);
> 
>  			xe_ggtt_set_pte(ggtt, *ggtt_ofs, pte); @@ -381,4
> +381,4 @@ struct i915_address_space *intel_dpt_create(struct
> intel_framebuffer *fb)  void intel_dpt_destroy(struct i915_address_space *vm)
> {
>  	return;
> -}
> \ No newline at end of file
> +}
> --
> 2.25.1