[FFmpeg-devel] [PATCH] sws_scale: Use av_sat_add32 in yuv2rgba64 template

Drew Dunne asdunne at google.com
Tue Nov 1 21:05:07 EET 2022


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



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