This was supposed to be in reply to a previous patch I sent, but I changed
the git message so maybe it didn't like that. Sorry about that.

Attached is the example YUVA file that can reproduce the overflow bug.

The command to reproduce is:

./ffmpeg \
  -f rawvideo -video_size 66x64 -pixel_format yuva420p10le \
  -i overflow_input_w66h64.yuva420p10le \
  -filter_complex
"scale=flags=bicubic+full_chroma_int+full_chroma_inp+bitexact+accurate_rnd:in_color_matrix=bt2020:out_color_matrix=bt2020:in_range=full:out_range=full,format=rgba64[out]"
\
  -f rawvideo -codec:v:0 rawvideo -pixel_format rgba64 -map '[out]' \
  -y overflow_w66h64.rgba64

I've attached a PNG of the resulting overflowed image, there is a clear
discoloration in the bottom left corner that's orange instead of pink.

I've also attached a PNG of the image using the patch to correct this
overflow.



On Tue, Nov 1, 2022 at 3:05 PM Drew Dunne <asdunne@google.com> wrote:

> Avoid a possible integer overflow in the yuv2rgba64 templates by using
> av_sat_add32 when combing the R, G, B components with Y. On certain
> inputs, this addition can overflow to a negative, is then clipped to a
> power of two and shifted down 14. This results in a much different value
> in the output than had it been saturated instead. I will attach an
> example input YUV in a follow up and some images that show the artifacts
> resulting from this overflow.
>
> ---
>  libswscale/output.c | 96 ++++++++++++++++++++++-----------------------
>  1 file changed, 48 insertions(+), 48 deletions(-)
>
> diff --git a/libswscale/output.c b/libswscale/output.c
> index 0e1c1225a0..8c8f62682a 100644
> --- a/libswscale/output.c
> +++ b/libswscale/output.c
> @@ -1109,20 +1109,20 @@ yuv2rgba64_X_c_template(SwsContext *c, const
> int16_t *lumFilter,
>          B =                            U * c->yuv2rgb_u2b_coeff;
>
>          // 8 bits: 30 - 22 = 8 bits, 16 bits: 30 bits - 14 = 16 bits
> -        output_pixel(&dest[0], av_clip_uintp2(R_B + Y1, 30) >> 14);
> -        output_pixel(&dest[1], av_clip_uintp2(  G + Y1, 30) >> 14);
> -        output_pixel(&dest[2], av_clip_uintp2(B_R + Y1, 30) >> 14);
> +        output_pixel(&dest[0], av_clip_uintp2(av_sat_add32(R_B, Y1), 30)
> >> 14);
> +        output_pixel(&dest[1], av_clip_uintp2(av_sat_add32(  G, Y1), 30)
> >> 14);
> +        output_pixel(&dest[2], av_clip_uintp2(av_sat_add32(B_R, Y1), 30)
> >> 14);
>          if (eightbytes) {
>              output_pixel(&dest[3], av_clip_uintp2(A1      , 30) >> 14);
> -            output_pixel(&dest[4], av_clip_uintp2(R_B + Y2, 30) >> 14);
> -            output_pixel(&dest[5], av_clip_uintp2(  G + Y2, 30) >> 14);
> -            output_pixel(&dest[6], av_clip_uintp2(B_R + Y2, 30) >> 14);
> +            output_pixel(&dest[4], av_clip_uintp2(av_sat_add32(R_B, Y2),
> 30) >> 14);
> +            output_pixel(&dest[5], av_clip_uintp2(av_sat_add32(  G, Y2),
> 30) >> 14);
> +            output_pixel(&dest[6], av_clip_uintp2(av_sat_add32(B_R, Y2),
> 30) >> 14);
>              output_pixel(&dest[7], av_clip_uintp2(A2      , 30) >> 14);
>              dest += 8;
>          } else {
> -            output_pixel(&dest[3], av_clip_uintp2(R_B + Y2, 30) >> 14);
> -            output_pixel(&dest[4], av_clip_uintp2(  G + Y2, 30) >> 14);
> -            output_pixel(&dest[5], av_clip_uintp2(B_R + Y2, 30) >> 14);
> +            output_pixel(&dest[3], av_clip_uintp2(av_sat_add32(R_B, Y2),
> 30) >> 14);
> +            output_pixel(&dest[4], av_clip_uintp2(av_sat_add32(  G, Y2),
> 30) >> 14);
> +            output_pixel(&dest[5], av_clip_uintp2(av_sat_add32(B_R, Y2),
> 30) >> 14);
>              dest += 6;
>          }
>      }
> @@ -1175,20 +1175,20 @@ yuv2rgba64_2_c_template(SwsContext *c, const
> int32_t *buf[2],
>              A2 += 1 << 13;
>          }
>
> -        output_pixel(&dest[0], av_clip_uintp2(R_B + Y1, 30) >> 14);
> -        output_pixel(&dest[1], av_clip_uintp2(  G + Y1, 30) >> 14);
> -        output_pixel(&dest[2], av_clip_uintp2(B_R + Y1, 30) >> 14);
> +        output_pixel(&dest[0], av_clip_uintp2(av_sat_add32(R_B, Y1), 30)
> >> 14);
> +        output_pixel(&dest[1], av_clip_uintp2(av_sat_add32(  G, Y1), 30)
> >> 14);
> +        output_pixel(&dest[2], av_clip_uintp2(av_sat_add32(B_R, Y1), 30)
> >> 14);
>          if (eightbytes) {
>              output_pixel(&dest[3], av_clip_uintp2(A1      , 30) >> 14);
> -            output_pixel(&dest[4], av_clip_uintp2(R_B + Y2, 30) >> 14);
> -            output_pixel(&dest[5], av_clip_uintp2(  G + Y2, 30) >> 14);
> -            output_pixel(&dest[6], av_clip_uintp2(B_R + Y2, 30) >> 14);
> +            output_pixel(&dest[4], av_clip_uintp2(av_sat_add32(R_B, Y2),
> 30) >> 14);
> +            output_pixel(&dest[5], av_clip_uintp2(av_sat_add32(  G, Y2),
> 30) >> 14);
> +            output_pixel(&dest[6], av_clip_uintp2(av_sat_add32(B_R, Y2),
> 30) >> 14);
>              output_pixel(&dest[7], av_clip_uintp2(A2      , 30) >> 14);
>              dest += 8;
>          } else {
> -            output_pixel(&dest[3], av_clip_uintp2(R_B + Y2, 30) >> 14);
> -            output_pixel(&dest[4], av_clip_uintp2(  G + Y2, 30) >> 14);
> -            output_pixel(&dest[5], av_clip_uintp2(B_R + Y2, 30) >> 14);
> +            output_pixel(&dest[3], av_clip_uintp2(av_sat_add32(R_B, Y2),
> 30) >> 14);
> +            output_pixel(&dest[4], av_clip_uintp2(av_sat_add32(  G, Y2),
> 30) >> 14);
> +            output_pixel(&dest[5], av_clip_uintp2(av_sat_add32(B_R, Y2),
> 30) >> 14);
>              dest += 6;
>          }
>      }
> @@ -1232,20 +1232,20 @@ yuv2rgba64_1_c_template(SwsContext *c, const
> int32_t *buf0,
>              G = V * c->yuv2rgb_v2g_coeff + U * c->yuv2rgb_u2g_coeff;
>              B =                            U * c->yuv2rgb_u2b_coeff;
>
> -            output_pixel(&dest[0], av_clip_uintp2(R_B + Y1, 30) >> 14);
> -            output_pixel(&dest[1], av_clip_uintp2(  G + Y1, 30) >> 14);
> -            output_pixel(&dest[2], av_clip_uintp2(B_R + Y1, 30) >> 14);
> +            output_pixel(&dest[0], av_clip_uintp2(av_sat_add32(R_B, Y1),
> 30) >> 14);
> +            output_pixel(&dest[1], av_clip_uintp2(av_sat_add32(  G, Y1),
> 30) >> 14);
> +            output_pixel(&dest[2], av_clip_uintp2(av_sat_add32(B_R, Y1),
> 30) >> 14);
>              if (eightbytes) {
>                  output_pixel(&dest[3], av_clip_uintp2(A1      , 30) >>
> 14);
> -                output_pixel(&dest[4], av_clip_uintp2(R_B + Y2, 30) >>
> 14);
> -                output_pixel(&dest[5], av_clip_uintp2(  G + Y2, 30) >>
> 14);
> -                output_pixel(&dest[6], av_clip_uintp2(B_R + Y2, 30) >>
> 14);
> +                output_pixel(&dest[4], av_clip_uintp2(av_sat_add32(R_B,
> Y2), 30) >> 14);
> +                output_pixel(&dest[5], av_clip_uintp2(av_sat_add32(  G,
> Y2), 30) >> 14);
> +                output_pixel(&dest[6], av_clip_uintp2(av_sat_add32(B_R,
> Y2), 30) >> 14);
>                  output_pixel(&dest[7], av_clip_uintp2(A2      , 30) >>
> 14);
>                  dest += 8;
>              } else {
> -                output_pixel(&dest[3], av_clip_uintp2(R_B + Y2, 30) >>
> 14);
> -                output_pixel(&dest[4], av_clip_uintp2(  G + Y2, 30) >>
> 14);
> -                output_pixel(&dest[5], av_clip_uintp2(B_R + Y2, 30) >>
> 14);
> +                output_pixel(&dest[3], av_clip_uintp2(av_sat_add32(R_B,
> Y2), 30) >> 14);
> +                output_pixel(&dest[4], av_clip_uintp2(av_sat_add32(  G,
> Y2), 30) >> 14);
> +                output_pixel(&dest[5], av_clip_uintp2(av_sat_add32(B_R,
> Y2), 30) >> 14);
>                  dest += 6;
>              }
>          }
> @@ -1278,20 +1278,20 @@ yuv2rgba64_1_c_template(SwsContext *c, const
> int32_t *buf0,
>              G = V * c->yuv2rgb_v2g_coeff + U * c->yuv2rgb_u2g_coeff;
>              B =                            U * c->yuv2rgb_u2b_coeff;
>
> -            output_pixel(&dest[0], av_clip_uintp2(R_B + Y1, 30) >> 14);
> -            output_pixel(&dest[1], av_clip_uintp2(  G + Y1, 30) >> 14);
> -            output_pixel(&dest[2], av_clip_uintp2(B_R + Y1, 30) >> 14);
> +            output_pixel(&dest[0], av_clip_uintp2(av_sat_add32(R_B, Y1),
> 30) >> 14);
> +            output_pixel(&dest[1], av_clip_uintp2(av_sat_add32(  G, Y1),
> 30) >> 14);
> +            output_pixel(&dest[2], av_clip_uintp2(av_sat_add32(B_R, Y1),
> 30) >> 14);
>              if (eightbytes) {
>                  output_pixel(&dest[3], av_clip_uintp2(A1      , 30) >>
> 14);
> -                output_pixel(&dest[4], av_clip_uintp2(R_B + Y2, 30) >>
> 14);
> -                output_pixel(&dest[5], av_clip_uintp2(  G + Y2, 30) >>
> 14);
> -                output_pixel(&dest[6], av_clip_uintp2(B_R + Y2, 30) >>
> 14);
> +                output_pixel(&dest[4], av_clip_uintp2(av_sat_add32(R_B,
> Y2), 30) >> 14);
> +                output_pixel(&dest[5], av_clip_uintp2(av_sat_add32(  G,
> Y2), 30) >> 14);
> +                output_pixel(&dest[6], av_clip_uintp2(av_sat_add32(B_R,
> Y2), 30) >> 14);
>                  output_pixel(&dest[7], av_clip_uintp2(A2      , 30) >>
> 14);
>                  dest += 8;
>              } else {
> -                output_pixel(&dest[3], av_clip_uintp2(R_B + Y2, 30) >>
> 14);
> -                output_pixel(&dest[4], av_clip_uintp2(  G + Y2, 30) >>
> 14);
> -                output_pixel(&dest[5], av_clip_uintp2(B_R + Y2, 30) >>
> 14);
> +                output_pixel(&dest[3], av_clip_uintp2(av_sat_add32(R_B,
> Y2), 30) >> 14);
> +                output_pixel(&dest[4], av_clip_uintp2(av_sat_add32(  G,
> Y2), 30) >> 14);
> +                output_pixel(&dest[5], av_clip_uintp2(av_sat_add32(B_R,
> Y2), 30) >> 14);
>                  dest += 6;
>              }
>          }
> @@ -1351,9 +1351,9 @@ yuv2rgba64_full_X_c_template(SwsContext *c, const
> int16_t *lumFilter,
>          B =                            U * c->yuv2rgb_u2b_coeff;
>
>          // 8bit: 30 - 22 = 8bit, 16bit: 30bit - 14 = 16bit
> -        output_pixel(&dest[0], av_clip_uintp2(R_B + Y, 30) >> 14);
> -        output_pixel(&dest[1], av_clip_uintp2(  G + Y, 30) >> 14);
> -        output_pixel(&dest[2], av_clip_uintp2(B_R + Y, 30) >> 14);
> +        output_pixel(&dest[0], av_clip_uintp2(av_sat_add32(R_B, Y), 30)
> >> 14);
> +        output_pixel(&dest[1], av_clip_uintp2(av_sat_add32(  G, Y), 30)
> >> 14);
> +        output_pixel(&dest[2], av_clip_uintp2(av_sat_add32(B_R, Y), 30)
> >> 14);
>          if (eightbytes) {
>              output_pixel(&dest[3], av_clip_uintp2(A, 30) >> 14);
>              dest += 4;
> @@ -1404,9 +1404,9 @@ yuv2rgba64_full_2_c_template(SwsContext *c, const
> int32_t *buf[2],
>              A += 1 << 13;
>          }
>
> -        output_pixel(&dest[0], av_clip_uintp2(R_B + Y, 30) >> 14);
> -        output_pixel(&dest[1], av_clip_uintp2(  G + Y, 30) >> 14);
> -        output_pixel(&dest[2], av_clip_uintp2(B_R + Y, 30) >> 14);
> +        output_pixel(&dest[0], av_clip_uintp2(av_sat_add32(R_B, Y), 30)
> >> 14);
> +        output_pixel(&dest[1], av_clip_uintp2(av_sat_add32(  G, Y), 30)
> >> 14);
> +        output_pixel(&dest[2], av_clip_uintp2(av_sat_add32(B_R, Y), 30)
> >> 14);
>          if (eightbytes) {
>              output_pixel(&dest[3], av_clip_uintp2(A, 30) >> 14);
>              dest += 4;
> @@ -1448,9 +1448,9 @@ yuv2rgba64_full_1_c_template(SwsContext *c, const
> int32_t *buf0,
>              G = V * c->yuv2rgb_v2g_coeff + U * c->yuv2rgb_u2g_coeff;
>              B =                            U * c->yuv2rgb_u2b_coeff;
>
> -            output_pixel(&dest[0], av_clip_uintp2(R_B + Y, 30) >> 14);
> -            output_pixel(&dest[1], av_clip_uintp2(  G + Y, 30) >> 14);
> -            output_pixel(&dest[2], av_clip_uintp2(B_R + Y, 30) >> 14);
> +            output_pixel(&dest[0], av_clip_uintp2(av_sat_add32(R_B, Y),
> 30) >> 14);
> +            output_pixel(&dest[1], av_clip_uintp2(av_sat_add32(  G, Y),
> 30) >> 14);
> +            output_pixel(&dest[2], av_clip_uintp2(av_sat_add32(B_R, Y),
> 30) >> 14);
>              if (eightbytes) {
>                  output_pixel(&dest[3], av_clip_uintp2(A, 30) >> 14);
>                  dest += 4;
> @@ -1481,9 +1481,9 @@ yuv2rgba64_full_1_c_template(SwsContext *c, const
> int32_t *buf0,
>              G = V * c->yuv2rgb_v2g_coeff + U * c->yuv2rgb_u2g_coeff;
>              B =                            U * c->yuv2rgb_u2b_coeff;
>
> -            output_pixel(&dest[0], av_clip_uintp2(R_B + Y, 30) >> 14);
> -            output_pixel(&dest[1], av_clip_uintp2(  G + Y, 30) >> 14);
> -            output_pixel(&dest[2], av_clip_uintp2(B_R + Y, 30) >> 14);
> +            output_pixel(&dest[0], av_clip_uintp2(av_sat_add32(R_B, Y),
> 30) >> 14);
> +            output_pixel(&dest[1], av_clip_uintp2(av_sat_add32(  G, Y),
> 30) >> 14);
> +            output_pixel(&dest[2], av_clip_uintp2(av_sat_add32(B_R, Y),
> 30) >> 14);
>              if (eightbytes) {
>                  output_pixel(&dest[3], av_clip_uintp2(A, 30) >> 14);
>                  dest += 4;
> --
> 2.38.1.273.g43a17bfeac-goog
>
>

-- 
Drew Dunne
asdunne@google.com