[FFmpeg-devel] [PATCH 1/2] swscale/input: Use unsigned intermediates in rgb64ToUV_c_template

[Michael Niedermayer <michael@niedermayer.cc>]

From: Jeremy Dorfman <jdorfman@google.com>

Large rgb2yuv tables and high pixel values cause the intermediate
int32_t of ru*r + gu*g + bu*b to exceed INT_MAX, which is undefined
behavior. This causes libswscale built with LLVM -fsanitize=undefined to
assert. Using unsigned integers instead has defined behavior and
produces identical results, and makes rgb64ToUV_c_template match
rgb64ToY_c_template.

Fixes: signed integer overflow
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libswscale/input.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/libswscale/input.c b/libswscale/input.c
index 7ff7bfaa01..d7dbedd82f 100644
--- a/libswscale/input.c
+++ b/libswscale/input.c
@@ -65,9 +65,9 @@ rgb64ToUV_c_template(uint16_t *dstU, uint16_t *dstV,
     int32_t rv = rgb2yuv[RV_IDX], gv = rgb2yuv[GV_IDX], bv = rgb2yuv[BV_IDX];
     av_assert1(src1==src2);
     for (i = 0; i < width; i++) {
-        int r_b = input_pixel(&src1[i*4+0]);
-        int   g = input_pixel(&src1[i*4+1]);
-        int b_r = input_pixel(&src1[i*4+2]);
+        unsigned int r_b = input_pixel(&src1[i*4+0]);
+        unsigned int   g = input_pixel(&src1[i*4+1]);
+        unsigned int b_r = input_pixel(&src1[i*4+2]);
 
         dstU[i] = (ru*r + gu*g + bu*b + (0x10001<<(RGB2YUV_SHIFT-1))) >> RGB2YUV_SHIFT;
         dstV[i] = (rv*r + gv*g + bv*b + (0x10001<<(RGB2YUV_SHIFT-1))) >> RGB2YUV_SHIFT;
-- 
2.17.1

_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel

To unsubscribe, visit link above, or email
ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".