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nutdec: reject negative value_len in read_sm_data

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If it is negative, it can cause the byte position to move backwards in
avio_skip, which in turn makes sm_size negative and thus size larger
than the size of the packet buffer, causing invalid writes in avio_read.

Also fix potential overflow of avio_tell(bc) + value_len.

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
(cherry picked from commit ce10f572c1)
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
This commit is contained in:
Andreas Cadhalpun 2015-12-19 12:02:56 +01:00
parent 882391f975
commit 2db78f83ba
1 changed files with 1 additions and 1 deletions
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2
libavformat/nutdec.c
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@ -872,7 +872,7 @@ static int read_sm_data(AVFormatContext *s, AVIOContext *bc, AVPacket *pkt, int
get_str(bc, type_str, sizeof(type_str));
value_len = ffio_read_varlen(bc);
if (avio_tell(bc) + value_len >= maxpos)
if (value_len < 0 || value_len >= maxpos - avio_tell(bc))
return AVERROR_INVALIDDATA;
if (!strcmp(name, "Palette")) {
dst = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE, value_len);