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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.

(cherry picked from commit e70c5b034c)

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
This commit is contained in:
Justin Ruggles 2012-12-10 12:44:09 -05:00 committed by Luca Barbato
parent 8c62082b51
commit e786cc3331
1 changed files with 19 additions and 3 deletions
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22
libavformat/swfdec.c
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@ -91,6 +91,10 @@ 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;
@ -150,7 +154,10 @@ 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;
@ -164,9 +171,14 @@ 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 == 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;
}
@ -193,7 +205,10 @@ 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 ||
@ -210,6 +225,7 @@ static int swf_read_packet(AVFormatContext *s, AVPacket *pkt)
return pkt->size;
}
skip:
len = FFMAX(0, len);
avio_skip(pb, len);
}
}