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xan: Fixed out of bound accesses in xan_unpack() 

Signed-off-by: Janne Grunau <janne-libav@jannau.net>
This commit is contained in:
Laurent Aimar 2011-09-29 03:12:07 +00:00 committed by Janne Grunau
parent 1cd0a55163
commit 3e0757c2a8
1 changed files with 13 additions and 5 deletions
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18
libavcodec/xan.c
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@ -130,13 +130,16 @@ static int xan_huffman_decode(unsigned char *dest, int dest_len,
*
* @param dest destination buffer of dest_len, must be padded with at least 130 bytes
*/
static void xan_unpack(unsigned char *dest, const unsigned char *src, int dest_len)
static void xan_unpack(unsigned char *dest, int dest_len,
const unsigned char *src, int src_len)
{
unsigned char opcode;
int size;
unsigned char *dest_org = dest;
unsigned char *dest_end = dest + dest_len;
const unsigned char *src_end = src + src_len;
while (dest < dest_end) {
while (dest < dest_end && src < src_end) {
opcode = *src++;
if (opcode < 0xe0) {
@ -161,9 +164,11 @@ static void xan_unpack(unsigned char *dest, const unsigned char *src, int dest_l
back = ((opcode & 0x10) << 12) + bytestream_get_be16(&src) + 1;
size2 = ((opcode & 0x0c) << 6) + *src++ + 5;
if (size + size2 > dest_end - dest)
return;
}
if (dest_end - dest < size + size2 ||
dest + size - dest_org < back ||
src_end - src < size)
return;
memcpy(dest, src, size); dest += size; src += size;
av_memcpy_backptr(dest, back, size2);
dest += size2;
@ -171,6 +176,8 @@ static void xan_unpack(unsigned char *dest, const unsigned char *src, int dest_l
int finish = opcode >= 0xfc;
size = finish ? opcode & 3 : ((opcode & 0x1f) << 2) + 4;
if (dest_end - dest < size || src_end - src < size)
return;
memcpy(dest, src, size); dest += size; src += size;
if (finish)
return;
@ -303,7 +310,8 @@ static int xan_wc3_decode_frame(XanContext *s) {
return AVERROR_INVALIDDATA;
if (imagedata_segment[0] == 2) {
xan_unpack(s->buffer2, &imagedata_segment[1], s->buffer2_size);
xan_unpack(s->buffer2, s->buffer2_size,
&imagedata_segment[1], s->size - imagedata_offset - 1);
imagedata_size = s->buffer2_size;
} else {
imagedata_size = s->size - imagedata_offset - 1;