avcodec/osq: Treat sum = 0 as k = 0
We have no valid sample that triggers this so we do not know if this would decode
correctly, but -inf is not the correct k value
Fixes: Assertion n>=0 && n<=32 failed at libavcodec/get_bits.h:423
Fixes: -inf is outside the range of representable values of type 'int'
Fixes: 70709/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_OSQ_fuzzer-6223623839350784
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
diff --git a/libavcodec/osq.c b/libavcodec/osq.c
index 4e92189..2b75364 100644
--- a/libavcodec/osq.c
+++ b/libavcodec/osq.c
@@ -160,6 +160,8 @@
int rice_k;
sum = cb->sum;
+ if (!sum)
+ return 0;
x = sum / cb->count;
rice_k = ceil(log2(x));
if (rice_k >= 30) {
