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mxfdec: Never seek back in local sets and KLVs 

Specially crafted files can lead the parsing code to take too long.
We fix a lot of these problems by not allowing local tags to extend
past the end of the set and not allowing other KLVs to be read past
the end of themselves.

Signed-off-by: Diego Biurrun <diego@biurrun.de>
This commit is contained in:
Tomas Härdin 2012-01-26 13:21:38 +01:00 committed by Diego Biurrun
parent 687e2fdebd
commit 11800c8c89
1 changed files with 17 additions and 1 deletions
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18
libavformat/mxfdec.c
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@ -1499,7 +1499,15 @@ static int mxf_read_local_tags(MXFContext *mxf, KLVPacket *klv, MXFMetadataReadF
else if ((ret = read_child(ctx, pb, tag, size, uid, -1)) < 0)
return ret;
avio_seek(pb, next, SEEK_SET);
/* Accept the 64k local set limit being exceeded (Avid). Don't accept
* it extending past the end of the KLV though (zzuf5.mxf). */
if (avio_tell(pb) > klv_end) {
av_log(mxf->fc, AV_LOG_ERROR,
"local tag %#04x extends past end of local set @ %#"PRIx64"\n",
tag, klv->offset);
return AVERROR_INVALIDDATA;
} else if (avio_tell(pb) <= next) /* only seek forward, else this can loop for a long time */
avio_seek(pb, next, SEEK_SET);
}
if (ctx_size) ctx->type = type;
return ctx_size ? mxf_add_metadata_set(mxf, ctx) : 0;
@ -1717,6 +1725,14 @@ static int mxf_read_header(AVFormatContext *s)
} else {
uint64_t next = avio_tell(s->pb) + klv.length;
res = metadata->read(mxf, s->pb, 0, klv.length, klv.key, klv.offset);
/* only seek forward, else this can loop for a long time */
if (avio_tell(s->pb) > next) {
av_log(s, AV_LOG_ERROR, "read past end of KLV @ %#"PRIx64"\n",
klv.offset);
return AVERROR_INVALIDDATA;
}
avio_seek(s->pb, next, SEEK_SET);
}
if (res < 0) {