NFSD: pass null terminated buf to kstrtouint()

The 'buf' is prepared with null termination with intention of using it for
this purpose, but 'name' is passed instead!
Signed-off-by: Malahal Naineni <malahal@us.ibm.com>
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4idmap.c

@@ -598,7 +598,7 @@ numeric_name_to_id(struct svc_rqst *rqstp, int type, const char *name, u32 namel
 	/* Just to make sure it's null-terminated: */
 	memcpy(buf, name, namelen);
 	buf[namelen] = '\0';
-	ret = kstrtouint(name, 10, id);
+	ret = kstrtouint(buf, 10, id);
 	return ret == 0;
 }