[FFmpeg-devel] [PATCH 3/6] swscale/output: Fix integer overflow in yuv2rgba64_full_1_c_template()

[Michael Niedermayer]

Fixes: signed integer overflow: -1082982400 + -1079364728 cannot be represented in type 'int'
Fixes: 67910/clusterfuzz-testcase-minimized-ffmpeg_SWS_fuzzer-5329011971522560
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 | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/libswscale/output.c b/libswscale/output.c
index 0b6c77e167d..b234f9c6b9a 100644
--- a/libswscale/output.c
+++ b/libswscale/output.c
@@ -1429,7 +1429,7 @@ yuv2rgba64_full_1_c_template(SwsContext *c, const int32_t *buf0,
 
     if (uvalpha < 2048) {
         for (i = 0; i < dstW; i++) {
-            int Y  = (buf0[i]) >> 2;
+            SUINT Y  = (buf0[i]) >> 2;
             int U  = (ubuf0[i] - (128 << 11)) >> 2;
             int V  = (vbuf0[i] - (128 << 11)) >> 2;
             int R, G, B;
@@ -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) >> 14) + (1<<15), 16));
-            output_pixel(&dest[1], av_clip_uintp2(((  G + Y) >> 14) + (1<<15), 16));
-            output_pixel(&dest[2], av_clip_uintp2(((B_R + Y) >> 14) + (1<<15), 16));
+            output_pixel(&dest[0], av_clip_uintp2(((int)(R_B + Y) >> 14) + (1<<15), 16));
+            output_pixel(&dest[1], av_clip_uintp2(((int)(  G + Y) >> 14) + (1<<15), 16));
+            output_pixel(&dest[2], av_clip_uintp2(((int)(B_R + Y) >> 14) + (1<<15), 16));
             if (eightbytes) {
                 output_pixel(&dest[3], av_clip_uintp2(A, 30) >> 14);
                 dest += 4;
@@ -1462,7 +1462,7 @@ yuv2rgba64_full_1_c_template(SwsContext *c, const int32_t *buf0,
         const int32_t *ubuf1 = ubuf[1], *vbuf1 = vbuf[1];
         int A = 0xffff<<14;
         for (i = 0; i < dstW; i++) {
-            int Y  = (buf0[i]    ) >> 2;
+            SUINT Y  = (buf0[i]    ) >> 2;
             int U  = (ubuf0[i] + ubuf1[i] - (128 << 12)) >> 3;
             int V  = (vbuf0[i] + vbuf1[i] - (128 << 12)) >> 3;
             int R, G, B;
@@ -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) >> 14) + (1<<15), 16));
-            output_pixel(&dest[1], av_clip_uintp2(((  G + Y) >> 14) + (1<<15), 16));
-            output_pixel(&dest[2], av_clip_uintp2(((B_R + Y) >> 14) + (1<<15), 16));
+            output_pixel(&dest[0], av_clip_uintp2(((int)(R_B + Y) >> 14) + (1<<15), 16));
+            output_pixel(&dest[1], av_clip_uintp2(((int)(  G + Y) >> 14) + (1<<15), 16));
+            output_pixel(&dest[2], av_clip_uintp2(((int)(B_R + Y) >> 14) + (1<<15), 16));
             if (eightbytes) {
                 output_pixel(&dest[3], av_clip_uintp2(A, 30) >> 14);
                 dest += 4;
-- 
2.43.2