One fix for a bug that could cause a NULL write past the end of a buffer

in case of unusually long writes to some system interfaces used by
 mountd and other nfs support utilities.
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Merge tag 'nfsd-4.5-1' of git://linux-nfs.org/~bfields/linux

Pull nfsd bugfix from Bruce Fields:
 "One fix for a bug that could cause a NULL write past the end of a
  buffer in case of unusually long writes to some system interfaces used
  by mountd and other nfs support utilities"

* tag 'nfsd-4.5-1' of git://linux-nfs.org/~bfields/linux:
  sunrpc/cache: fix off-by-one in qword_get()

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]);