[FFmpeg-cvslog] avcodec/alsdec: fix mantisse shift
Michael Niedermayer
git at videolan.org
Sun Aug 11 20:15:57 EEST 2019
ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Fri Jul 26 17:07:01 2019 +0200| [02346292a334a51f6da802146b782bdb01ae9b4e] | committer: Michael Niedermayer
avcodec/alsdec: fix mantisse shift
Fixes: shift exponent -1 is negative
Fixes: 16039/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ALS_fuzzer-5656825657032704
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=02346292a334a51f6da802146b782bdb01ae9b4e
---
libavcodec/alsdec.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/libavcodec/alsdec.c b/libavcodec/alsdec.c
index d4451482a4..e1449a72a5 100644
--- a/libavcodec/alsdec.c
+++ b/libavcodec/alsdec.c
@@ -1404,7 +1404,11 @@ static SoftFloat_IEEE754 multiply(SoftFloat_IEEE754 a, SoftFloat_IEEE754 b) {
}
}
- mantissa = (unsigned int)(mantissa_temp >> cutoff_bit_count);
+ if (cutoff_bit_count >= 0) {
+ mantissa = (unsigned int)(mantissa_temp >> cutoff_bit_count);
+ } else {
+ mantissa = (unsigned int)(mantissa_temp <<-cutoff_bit_count);
+ }
// Need one more shift?
if (mantissa & 0x01000000ul) {
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