Packets without data need to be handled specially in order to avoid undefined reads. Pass these packets through unchanged in case there are no cached packets* and error out in case there are cached packets: Returning the packet would mess with the order of the packets; if one returned the zero-sized packet before the superframe that will be created from the packets in the cache, the zero-sized packet would overtake the packets in the cache; if one returned the packet later, the packets that complete the superframe will overtake the zero-sized packet.
*: This case e.g. encompasses the scenario of updated extradata side-data at the end. Fixes: Out of array read Fixes: 45722/clusterfuzz-testcase-minimized-ffmpeg_BSF_VP9_SUPERFRAME_fuzzer-5173378975137792 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@outlook.com> --- The current way of passthrough has been suggested by James. libavcodec/vp9_superframe_bsf.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/libavcodec/vp9_superframe_bsf.c b/libavcodec/vp9_superframe_bsf.c index 57681e29e4..df9b97fa3c 100644 --- a/libavcodec/vp9_superframe_bsf.c +++ b/libavcodec/vp9_superframe_bsf.c @@ -108,6 +108,15 @@ static int vp9_superframe_filter(AVBSFContext *ctx, AVPacket *pkt) if (res < 0) return res; + if (!pkt->size) { + /* In case the cache is empty we can pass side-data-only packets + * through unchanged. Otherwise, such a packet makes no sense. */ + if (!s->n_cache) + return 0; + res = AVERROR_INVALIDDATA; + goto done; + } + marker = pkt->data[pkt->size - 1]; if ((marker & 0xe0) == 0xc0) { int nbytes = 1 + ((marker >> 3) & 0x3); -- 2.32.0 _______________________________________________ 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".
