xtensa: ISS: fix call to split_if_spec

split_if_spec expects a NULL-pointer as an end marker for the argument
list, but tuntap_probe never supplied that terminating NULL. As a result
incorrectly formatted interface specification string may cause a crash
because of the random memory access. Fix that by adding NULL terminator
to the split_if_spec argument list.

Cc: stable@vger.kernel.org
Fixes: 7282bee7 ("[PATCH] xtensa: Architecture support for Tensilica Xtensa Part 8")
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

arch/xtensa/platforms/iss/network.c

@@ -237,7 +237,7 @@ static int tuntap_probe(struct iss_net_private *lp, int index, char *init)
 
 	init += sizeof(TRANSPORT_TUNTAP_NAME) - 1;
 	if (*init == ',') {
-		rem = split_if_spec(init + 1, &mac_str, &dev_name);
+		rem = split_if_spec(init + 1, &mac_str, &dev_name, NULL);
 		if (rem != NULL) {
 			pr_err("%s: extra garbage on specification : '%s'\n",
 			       dev->name, rem);