sunrpc/cache: fix off-by-one in qword_get()

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@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c
index 2b32fd602669..273bc3a35425 100644
--- a/net/sunrpc/cache.c
+++ b/net/sunrpc/cache.c
@@ -1225,7 +1225,7 @@ int qword_get(char **bpp, char *dest, int bufsize)
         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]);