[FFmpeg-devel] [PATCH 2/2] swscale/output: Avoid undefined overflow in yuv2rgb_write_full()

Michael Niedermayer michael at niedermayer.cc
Sun Jun 16 10:48:31 EEST 2024


Fixes: signed integer overflow: -140140 * 16525 cannot be represented in type 'int'
Fixes: 68859/clusterfuzz-testcase-minimized-ffmpeg_SWS_fuzzer-4516387130245120

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 | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/libswscale/output.c b/libswscale/output.c
index f9ce43dde80..0e6181b3e01 100644
--- a/libswscale/output.c
+++ b/libswscale/output.c
@@ -1925,9 +1925,9 @@ static av_always_inline void yuv2rgb_write_full(SwsContext *c,
     Y -= c->yuv2rgb_y_offset;
     Y *= c->yuv2rgb_y_coeff;
     Y += 1 << 21;
-    R = (unsigned)Y + V*c->yuv2rgb_v2r_coeff;
-    G = (unsigned)Y + V*c->yuv2rgb_v2g_coeff + U*c->yuv2rgb_u2g_coeff;
-    B = (unsigned)Y +                          U*c->yuv2rgb_u2b_coeff;
+    R = (unsigned)Y + V*(unsigned)c->yuv2rgb_v2r_coeff;
+    G = (unsigned)Y + V*(unsigned)c->yuv2rgb_v2g_coeff + U*(unsigned)c->yuv2rgb_u2g_coeff;
+    B = (unsigned)Y +                                    U*(unsigned)c->yuv2rgb_u2b_coeff;
     if ((R | G | B) & 0xC0000000) {
         R = av_clip_uintp2(R, 30);
         G = av_clip_uintp2(G, 30);
-- 
2.45.2



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