[FFmpeg-devel] [PATCH 2/6] swscale/output: Fix integer overflow in yuv2rgba64_1_c_template

[Michael Niedermayer]

Fixes: signed integer overflow: -831176 * 9539 cannot be represented in type 'int'
Fixes: 67869/clusterfuzz-testcase-minimized-ffmpeg_SWS_fuzzer-5117342091640832

The input is 9bit in 16bit, the fuzzer fills all 16bit thus generating "invalid" input
No overflow should happen with valid input.

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
---
 libswscale/output.c | 44 ++++++++++++++++++++++----------------------
 1 file changed, 22 insertions(+), 22 deletions(-)

diff --git a/libswscale/output.c b/libswscale/output.c
index 8849a3201a6..0b6c77e167d 100644
--- a/libswscale/output.c
+++ b/libswscale/output.c
@@ -1207,8 +1207,8 @@ yuv2rgba64_1_c_template(SwsContext *c, const int32_t *buf0,
 
     if (uvalpha < 2048) {
         for (i = 0; i < ((dstW + 1) >> 1); i++) {
-            int Y1 = (buf0[i * 2]    ) >> 2;
-            int Y2 = (buf0[i * 2 + 1]) >> 2;
+            SUINT Y1 = (buf0[i * 2]    ) >> 2;
+            SUINT Y2 = (buf0[i * 2 + 1]) >> 2;
             int U  = (ubuf0[i] - (128 << 11)) >> 2;
             int V  = (vbuf0[i] - (128 << 11)) >> 2;
             int R, G, B;
@@ -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) >> 14) + (1<<15), 16));
-            output_pixel(&dest[1], av_clip_uintp2(((  G + Y1) >> 14) + (1<<15), 16));
-            output_pixel(&dest[2], av_clip_uintp2(((B_R + Y1) >> 14) + (1<<15), 16));
+            output_pixel(&dest[0], av_clip_uintp2(((int)(R_B + Y1) >> 14) + (1<<15), 16));
+            output_pixel(&dest[1], av_clip_uintp2(((int)(  G + Y1) >> 14) + (1<<15), 16));
+            output_pixel(&dest[2], av_clip_uintp2(((int)(B_R + Y1) >> 14) + (1<<15), 16));
             if (eightbytes) {
                 output_pixel(&dest[3], av_clip_uintp2(A1      , 30) >> 14);
-                output_pixel(&dest[4], av_clip_uintp2(((R_B + Y2) >> 14) + (1<<15), 16));
-                output_pixel(&dest[5], av_clip_uintp2(((  G + Y2) >> 14) + (1<<15), 16));
-                output_pixel(&dest[6], av_clip_uintp2(((B_R + Y2) >> 14) + (1<<15), 16));
+                output_pixel(&dest[4], av_clip_uintp2(((int)(R_B + Y2) >> 14) + (1<<15), 16));
+                output_pixel(&dest[5], av_clip_uintp2(((int)(  G + Y2) >> 14) + (1<<15), 16));
+                output_pixel(&dest[6], av_clip_uintp2(((int)(B_R + Y2) >> 14) + (1<<15), 16));
                 output_pixel(&dest[7], av_clip_uintp2(A2      , 30) >> 14);
                 dest += 8;
             } else {
-                output_pixel(&dest[3], av_clip_uintp2(((R_B + Y2) >> 14) + (1<<15), 16));
-                output_pixel(&dest[4], av_clip_uintp2(((  G + Y2) >> 14) + (1<<15), 16));
-                output_pixel(&dest[5], av_clip_uintp2(((B_R + Y2) >> 14) + (1<<15), 16));
+                output_pixel(&dest[3], av_clip_uintp2(((int)(R_B + Y2) >> 14) + (1<<15), 16));
+                output_pixel(&dest[4], av_clip_uintp2(((int)(  G + Y2) >> 14) + (1<<15), 16));
+                output_pixel(&dest[5], av_clip_uintp2(((int)(B_R + Y2) >> 14) + (1<<15), 16));
                 dest += 6;
             }
         }
@@ -1253,8 +1253,8 @@ yuv2rgba64_1_c_template(SwsContext *c, const int32_t *buf0,
         const int32_t *ubuf1 = ubuf[1], *vbuf1 = vbuf[1];
         int A1 = 0xffff<<14, A2 = 0xffff<<14;
         for (i = 0; i < ((dstW + 1) >> 1); i++) {
-            int Y1 = (buf0[i * 2]    ) >> 2;
-            int Y2 = (buf0[i * 2 + 1]) >> 2;
+            SUINT Y1 = (buf0[i * 2]    ) >> 2;
+            SUINT Y2 = (buf0[i * 2 + 1]) >> 2;
             int U  = (ubuf0[i] + ubuf1[i] - (128 << 12)) >> 3;
             int V  = (vbuf0[i] + vbuf1[i] - (128 << 12)) >> 3;
             int R, G, B;
@@ -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) >> 14) + (1<<15), 16));
-            output_pixel(&dest[1], av_clip_uintp2(((  G + Y1) >> 14) + (1<<15), 16));
-            output_pixel(&dest[2], av_clip_uintp2(((B_R + Y1) >> 14) + (1<<15), 16));
+            output_pixel(&dest[0], av_clip_uintp2(((int)(R_B + Y1) >> 14) + (1<<15), 16));
+            output_pixel(&dest[1], av_clip_uintp2(((int)(  G + Y1) >> 14) + (1<<15), 16));
+            output_pixel(&dest[2], av_clip_uintp2(((int)(B_R + Y1) >> 14) + (1<<15), 16));
             if (eightbytes) {
                 output_pixel(&dest[3], av_clip_uintp2(A1      , 30) >> 14);
-                output_pixel(&dest[4], av_clip_uintp2(((R_B + Y2) >> 14) + (1<<15), 16));
-                output_pixel(&dest[5], av_clip_uintp2(((  G + Y2) >> 14) + (1<<15), 16));
-                output_pixel(&dest[6], av_clip_uintp2(((B_R + Y2) >> 14) + (1<<15), 16));
+                output_pixel(&dest[4], av_clip_uintp2(((int)(R_B + Y2) >> 14) + (1<<15), 16));
+                output_pixel(&dest[5], av_clip_uintp2(((int)(  G + Y2) >> 14) + (1<<15), 16));
+                output_pixel(&dest[6], av_clip_uintp2(((int)(B_R + Y2) >> 14) + (1<<15), 16));
                 output_pixel(&dest[7], av_clip_uintp2(A2      , 30) >> 14);
                 dest += 8;
             } else {
-                output_pixel(&dest[3], av_clip_uintp2(((R_B + Y2) >> 14) + (1<<15), 16));
-                output_pixel(&dest[4], av_clip_uintp2(((  G + Y2) >> 14) + (1<<15), 16));
-                output_pixel(&dest[5], av_clip_uintp2(((B_R + Y2) >> 14) + (1<<15), 16));
+                output_pixel(&dest[3], av_clip_uintp2(((int)(R_B + Y2) >> 14) + (1<<15), 16));
+                output_pixel(&dest[4], av_clip_uintp2(((int)(  G + Y2) >> 14) + (1<<15), 16));
+                output_pixel(&dest[5], av_clip_uintp2(((int)(B_R + Y2) >> 14) + (1<<15), 16));
                 dest += 6;
             }
         }
-- 
2.43.2