[FFmpeg-cvslog] avcodec/interplayacm: Fix overflow of last unused value

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Fri Oct 25 12:44:45 2019 +0200| [10eabb8e40df0ad84470d750f903917f4a05cb1f] | committer: Michael Niedermayer

avcodec/interplayacm: Fix overflow of last unused value

Fixes: signed integer overflow: -2147450880 - 65535 cannot be represented in type 'int'
Fixes: 18393/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_INTERPLAY_ACM_fuzzer-5667520110919680

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=10eabb8e40df0ad84470d750f903917f4a05cb1f
---

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

diff --git a/libavcodec/interplayacm.c b/libavcodec/interplayacm.c
index cff79eb6b2..3704d1a2f2 100644
--- a/libavcodec/interplayacm.c
+++ b/libavcodec/interplayacm.c
@@ -529,7 +529,7 @@ static int decode_block(InterplayACMContext *s)
 
     for (i = 1, x = -val; i <= count; i++) {
         s->midbuf[-i] = x;
-        x -= val;
+        x -= (unsigned)val;
     }
 
     ret = fill_block(s);