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check patch_delta bounds more carefully

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Let's avoid going south with invalid delta data.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
This commit is contained in:
Nicolas Pitre
2006-04-07 15:26:10 -04:00
committed by Junio C Hamano
parent 7d6c447145
commit 8960844a78
3 changed files with 28 additions and 9 deletions
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26
patch-delta.c
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@ -28,12 +28,12 @@ void *patch_delta(void *src_buf, unsigned long src_size,
top = delta_buf + delta_size;
/* make sure the orig file size matches what we expect */
size = get_delta_hdr_size(&data);
size = get_delta_hdr_size(&data, top);
if (size != src_size)
return NULL;
/* now the result size */
size = get_delta_hdr_size(&data);
size = get_delta_hdr_size(&data, top);
dst_buf = malloc(size + 1);
if (!dst_buf)
return NULL;
@ -52,21 +52,37 @@ void *patch_delta(void *src_buf, unsigned long src_size,
if (cmd & 0x20) cp_size |= (*data++ << 8);
if (cmd & 0x40) cp_size |= (*data++ << 16);
if (cp_size == 0) cp_size = 0x10000;
if (cp_off + cp_size < cp_size ||
cp_off + cp_size > src_size ||
cp_size > size)
goto bad;
memcpy(out, src_buf + cp_off, cp_size);
out += cp_size;
} else {
size -= cp_size;
} else if (cmd) {
if (cmd > size)
goto bad;
memcpy(out, data, cmd);
out += cmd;
data += cmd;
size -= cmd;
} else {
/*
* cmd == 0 is reserved for future encoding
* extensions. In the mean time we must fail when
* encountering them (might be data corruption).
*/
goto bad;
}
}
/* sanity check */
if (data != top || out - dst_buf != size) {
if (data != top || size != 0) {
bad:
free(dst_buf);
return NULL;
}
*dst_size = size;
*dst_size = out - dst_buf;
return dst_buf;
}