This might happen in avio_write() if size == 0 when the direct codepath is taken. It is undefined behaviour according to the spec although it happens to work in practice. Fixes the webm-webvtt-remux FATE-test under UBSan.
Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@outlook.com> --- libavformat/aviobuf.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/libavformat/aviobuf.c b/libavformat/aviobuf.c index b20b1a611a..5b6a42d7f4 100644 --- a/libavformat/aviobuf.c +++ b/libavformat/aviobuf.c @@ -231,6 +231,8 @@ void ffio_fill(AVIOContext *s, int b, int64_t count) void avio_write(AVIOContext *s, const unsigned char *buf, int size) { + if (size <= 0) + return; if (s->direct && !s->update_checksum) { avio_flush(s); writeout(s, buf, size); @@ -246,7 +248,7 @@ void avio_write(AVIOContext *s, const unsigned char *buf, int size) buf += len; size -= len; - } + } while (size > 0); } void avio_flush(AVIOContext *s) -- 2.34.1 _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".