tools/firewire: nosy-dump: check for allocation failure

Behavior of null pointer dereference is undefined in the C language.
Portably implement the desired behavior.

Reported-by: Yang Yeping <[e-mail]>
Signed-off-by: Stefan Richter <[e-mail]>

tools/firewire/nosy-dump.c

···
 
 	/* we put the ack in the subaction struct for easy access. */
 	sa = malloc(sizeof *sa - sizeof sa->packet + length);
+	if (!sa)
+		exit(EXIT_FAILURE);
 	sa->ack = data[length / 4 - 1];
 	sa->length = length;
 	memcpy(&sa->packet, data, length);
···
 	}
 
 	t = malloc(sizeof *t);
+	if (!t)
+		exit(EXIT_FAILURE);
 	t->request_node = request_node;
 	t->response_node = response_node;
 	t->tlabel = tlabel;