[FFmpeg-cvslog] avcodec/hdrdec: Update w in inner loop of decompress()

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Sun Sep 11 13:03:54 2022 +0200| [14e99cb47212a9b42956034337a00658bcace1ef] | committer: Michael Niedermayer

avcodec/hdrdec: Update w in inner loop of decompress()

Fixes: out of array access
Fixes: 50936/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_HDR_fuzzer-5423041009549312

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=14e99cb47212a9b42956034337a00658bcace1ef
---

 libavcodec/hdrdec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/hdrdec.c b/libavcodec/hdrdec.c
index 9b262f2ef2..7727826e2a 100644
--- a/libavcodec/hdrdec.c
+++ b/libavcodec/hdrdec.c
@@ -70,8 +70,8 @@ static int decompress(uint8_t *scanline, int w, GetByteContext *gb, const uint8_
             for (int i = run << rshift; i > 0 && w > 0 && scanline >= start + 4; i--) {
                 memcpy(scanline, scanline - 4, 4);
                 scanline += 4;
+                w -= 4;
             }
-            w -= run << rshift;
             rshift += 8;
             if (rshift > 16)
                 break;