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swfdec: do better validation of tag length

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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)

Conflicts:

	libavformat/swfdec.c
This commit is contained in:
Justin Ruggles
2012-12-10 12:44:09 -05:00
committed by Michael Niedermayer
parent 9c7c2abad4
commit d46713cc7e
1 changed files with 16 additions and 4 deletions
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20
libavformat/swfdec.c
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@@ -154,7 +154,7 @@ static int swf_read_packet(AVFormatContext *s, AVPacket *pkt)
if (tag < 0) if (tag < 0)
return tag; return tag;
if (len < 0) { if (len < 0) {
av_log(s, AV_LOG_ERROR, "len %d is invalid\n", len); av_log(s, AV_LOG_ERROR, "invalid tag length: %d\n", len);
return AVERROR_INVALIDDATA; return AVERROR_INVALIDDATA;
} }
if (tag == TAG_VIDEOSTREAM) { if (tag == TAG_VIDEOSTREAM) {
@@ -212,7 +212,10 @@ static int swf_read_packet(AVFormatContext *s, AVPacket *pkt)
st = s->streams[i]; st = s->streams[i];
if (st->codec->codec_type == AVMEDIA_TYPE_VIDEO && st->id == ch_id) { if (st->codec->codec_type == AVMEDIA_TYPE_VIDEO && st->id == ch_id) {
frame = avio_rl16(pb); 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; return res;
pkt->pos = pos; pkt->pos = pos;
pkt->pts = frame; pkt->pts = frame;
@@ -226,9 +229,14 @@ static int swf_read_packet(AVFormatContext *s, AVPacket *pkt)
if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO && st->id == -1) { if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO && st->id == -1) {
if (st->codec->codec_id == AV_CODEC_ID_MP3) { if (st->codec->codec_id == AV_CODEC_ID_MP3) {
avio_skip(pb, 4); 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; return res;
} else { // ADPCM, PCM } else { // ADPCM, PCM
if (len <= 0)
goto skip;
if ((res = av_get_packet(pb, pkt, len)) < 0) if ((res = av_get_packet(pb, pkt, len)) < 0)
return res; return res;
} }
@@ -254,7 +262,10 @@ static int swf_read_packet(AVFormatContext *s, AVPacket *pkt)
st = vst; st = vst;
} }
avio_rl16(pb); /* BITMAP_ID */ 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; return res;
avio_read(pb, pkt->data, 4); avio_read(pb, pkt->data, 4);
if (AV_RB32(pkt->data) == 0xffd8ffd9 || if (AV_RB32(pkt->data) == 0xffd8ffd9 ||
@@ -271,6 +282,7 @@ static int swf_read_packet(AVFormatContext *s, AVPacket *pkt)
return pkt->size; return pkt->size;
} }
skip: skip:
len = FFMAX(0, len);
avio_skip(pb, len); avio_skip(pb, len);
} }
} }