avformat/matroskadec: Check desc_bytes
Fixes: Division by 0
Fixes: 44035/clusterfuzz-testcase-minimized-ffmpeg_dem_WEBM_DASH_MANIFEST_fuzzer-4826721386364928
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <[email protected]>
diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
index 628cfda..31e5111 100644
--- a/libavformat/matroskadec.c
+++ b/libavformat/matroskadec.c
@@ -4216,12 +4216,16 @@
do {
int64_t desc_bytes = desc_end.end_offset - desc_beg.start_offset;
int64_t desc_ns = desc_end.end_time_ns - desc_beg.start_time_ns;
- double desc_sec = desc_ns / nano_seconds_per_second;
- double calc_bits_per_second = (desc_bytes * 8) / desc_sec;
+ double desc_sec, calc_bits_per_second, percent, mod_bits_per_second;
+ if (desc_bytes <= 0)
+ return -1;
+
+ desc_sec = desc_ns / nano_seconds_per_second;
+ calc_bits_per_second = (desc_bytes * 8) / desc_sec;
// Drop the bps by the percentage of bytes buffered.
- double percent = (desc_bytes - prebuffer_bytes) / desc_bytes;
- double mod_bits_per_second = calc_bits_per_second * percent;
+ percent = (desc_bytes - prebuffer_bytes) / desc_bytes;
+ mod_bits_per_second = calc_bits_per_second * percent;
if (prebuffer < desc_sec) {
double search_sec =
