[PATCH 3.14 126/130] sunrpc/cache: fix off-by-one in qword_get()

From: Greg Kroah-Hartman
Date: Tue Mar 01 2016 - 20:43:32 EST


3.14-stable review patch. If anyone has any objections, please let me know.

------------------

From: Stefan Hajnoczi <stefanha@xxxxxxxxxx>

commit b7052cd7bcf3c1478796e93e3dff2b44c9e82943 upstream.

The qword_get() function NUL-terminates its output buffer. If the input
string is in hex format \xXXXX... and the same length as the output
buffer, there is an off-by-one:

int qword_get(char **bpp, char *dest, int bufsize)
{
...
while (len < bufsize) {
...
*dest++ = (h << 4) | l;
len++;
}
...
*dest = '\0';
return len;
}

This patch ensures the NUL terminator doesn't fall outside the output
buffer.

Signed-off-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx>
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
net/sunrpc/cache.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/sunrpc/cache.c
+++ b/net/sunrpc/cache.c
@@ -1230,7 +1230,7 @@ int qword_get(char **bpp, char *dest, in
if (bp[0] == '\\' && bp[1] == 'x') {
/* HEX STRING */
bp += 2;
- while (len < bufsize) {
+ while (len < bufsize - 1) {
int h, l;

h = hex_to_bin(bp[0]);