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Fix possible buffer over-read in vorbis_comment, fix it double to be sure.

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First, make s signed, so that comparisons against end - p will not be made as
unsigned, making the check incorrectly pass if p is beyond end.
Also ensure that p will never be > end, so the code is correct also if
buf is not padded.

backported r20014 by reimar


Originally committed as revision 21711 to svn://svn.ffmpeg.org/ffmpeg/branches/0.5
This commit is contained in:
Reinhard Tartler 2010-02-09 18:51:11 +00:00
parent 7db16a8173
commit ef84190a1a
1 changed files with 5 additions and 4 deletions
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9
libavformat/oggparsevorbis.c
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@ -35,27 +35,28 @@ vorbis_comment(AVFormatContext * as, uint8_t *buf, int size)
{
const uint8_t *p = buf;
const uint8_t *end = buf + size;
unsigned s, n, j;
unsigned n, j;
int s;
if (size < 8) /* must have vendor_length and user_comment_list_length */
return -1;
s = bytestream_get_le32(&p);
if (end - p < s)
if (end - p - 4 < s || s < 0)
return -1;
p += s;
n = bytestream_get_le32(&p);
while (p < end && n > 0) {
while (end - p >= 4 && n > 0) {
const char *t, *v;
int tl, vl;
s = bytestream_get_le32(&p);
if (end - p < s)
if (end - p < s || s < 0)
break;
t = p;