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| author | Justin Ruggles <justin.ruggles@gmail.com> | 2012-12-10 12:44:09 -0500 |
|---|---|---|
| committer | Justin Ruggles <justin.ruggles@gmail.com> | 2012-12-11 09:36:26 -0500 |
| commit | e70c5b034c4787377e82cab2d5565486baec0c2a (patch) | |
| tree | 7a3d67b1f5dd4adc36bc874a1a6b331d9e5c033a | |
| parent | 02823f6d7188260dabb10c64d6dd74331e7772e0 (diff) | |
| download | ffmpeg-e70c5b034c4787377e82cab2d5565486baec0c2a.tar.gz | |
swfdec: do better validation of tag length
Avoids trying to read a packet with 0 or negative size.
Avoids a potential infinite loop due to seeking backwards.
Partially based on a patch by Michael Niedermayer.
| -rw-r--r-- | libavformat/swfdec.c | 22 |
1 files changed, 19 insertions, 3 deletions
diff --git a/libavformat/swfdec.c b/libavformat/swfdec.c index f105c141c6..d8a9852a89 100644 --- a/libavformat/swfdec.c +++ b/libavformat/swfdec.c @@ -100,6 +100,10 @@ static int swf_read_packet(AVFormatContext *s, AVPacket *pkt) tag = get_swf_tag(pb, &len); if (tag < 0) return AVERROR(EIO); + if (len < 0) { + av_log(s, AV_LOG_ERROR, "invalid tag length: %d\n", len); + return AVERROR_INVALIDDATA; + } if (tag == TAG_VIDEOSTREAM) { int ch_id = avio_rl16(pb); len -= 2; @@ -161,7 +165,10 @@ static int swf_read_packet(AVFormatContext *s, AVPacket *pkt) st = s->streams[i]; if (st->codec->codec_type == AVMEDIA_TYPE_VIDEO && st->id == ch_id) { frame = avio_rl16(pb); - if ((res = av_get_packet(pb, pkt, len-2)) < 0) + len -= 2; + if (len <= 0) + goto skip; + if ((res = av_get_packet(pb, pkt, len)) < 0) return res; pkt->pos = pos; pkt->pts = frame; @@ -175,9 +182,14 @@ static int swf_read_packet(AVFormatContext *s, AVPacket *pkt) if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO && st->id == -1) { if (st->codec->codec_id == AV_CODEC_ID_MP3) { avio_skip(pb, 4); - if ((res = av_get_packet(pb, pkt, len-4)) < 0) + len -= 4; + if (len <= 0) + goto skip; + if ((res = av_get_packet(pb, pkt, len)) < 0) return res; } else { // ADPCM, PCM + if (len <= 0) + goto skip; if ((res = av_get_packet(pb, pkt, len)) < 0) return res; } @@ -203,7 +215,10 @@ static int swf_read_packet(AVFormatContext *s, AVPacket *pkt) st = vst; } avio_rl16(pb); /* BITMAP_ID */ - if ((res = av_new_packet(pkt, len-2)) < 0) + len -= 2; + if (len < 4) + goto skip; + if ((res = av_new_packet(pkt, len)) < 0) return res; avio_read(pb, pkt->data, 4); if (AV_RB32(pkt->data) == 0xffd8ffd9 || @@ -220,6 +235,7 @@ static int swf_read_packet(AVFormatContext *s, AVPacket *pkt) return pkt->size; } skip: + len = FFMAX(0, len); avio_skip(pb, len); } } |