text ematch: check for NULL pointer before destroying textsearch config

While validating the configuration em_ops is already set, thus the
individual destroy functions are called, but the ematch data has
not been allocated and associated with the ematch yet.
Signed-off-by: NThomas Graf <tgraf@infradead.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/sched/em_text.c

@@ -103,7 +103,8 @@ static int em_text_change(struct tcf_proto *tp, void *data, int len,
 
 static void em_text_destroy(struct tcf_proto *tp, struct tcf_ematch *m)
 {
-	textsearch_destroy(EM_TEXT_PRIV(m)->config);
+	if (EM_TEXT_PRIV(m) && EM_TEXT_PRIV(m)->config)
+		textsearch_destroy(EM_TEXT_PRIV(m)->config);
 }
 
 static int em_text_dump(struct sk_buff *skb, struct tcf_ematch *m)