From a4fec9a7eab842ea5eea1b1ee98624356cb31422 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Mon, 5 Dec 2016 11:14:51 +0100 Subject: [PATCH] rtmppkt: Check for packet size mismatches MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When receiving fragmented packets, the first packet declares the size, and the later ones normally are small follow-on packets that don't repeat the size and the other header fields. But technically, the later fragments also can have a full header, declaring a different size than the previous packet. If the follow-on packet declares a larger size than the initial one, we could end up writing outside of the allocation. This fixes out of bounds writes. Found-by: Paul Cher Reviewed-by: Paul Cher CC: libav-stable@libav.org Signed-off-by: Martin Storsjö --- libavformat/rtmppkt.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/libavformat/rtmppkt.c b/libavformat/rtmppkt.c index f8c51d01fa..1cb3078679 100644 --- a/libavformat/rtmppkt.c +++ b/libavformat/rtmppkt.c @@ -235,6 +235,14 @@ static int rtmp_packet_read_one_chunk(URLContext *h, RTMPPacket *p, if (hdr != RTMP_PS_TWELVEBYTES) timestamp += prev_pkt[channel_id].timestamp; + if (prev_pkt[channel_id].read && size != prev_pkt[channel_id].size) { + av_log(h, AV_LOG_ERROR, "RTMP packet size mismatch %d != %d\n", + size, prev_pkt[channel_id].size); + ff_rtmp_packet_destroy(&prev_pkt[channel_id]); + prev_pkt[channel_id].read = 0; + return AVERROR_INVALIDDATA; + } + if (!prev_pkt[channel_id].read) { if ((ret = ff_rtmp_packet_create(p, channel_id, type, timestamp, size)) < 0)