cfg80211: fix mic_failure tracing

tsc can be NULL (mac80211 currently always passes NULL),
resulting in NULL-dereference. check before copying it.

Cc: stable@vger.kernel.org
Signed-off-by: NEliad Peller <eliadx.peller@intel.com>
Signed-off-by: NEmmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>

net/wireless/trace.h

@@ -2094,7 +2094,8 @@ TRACE_EVENT(cfg80211_michael_mic_failure,
 		MAC_ASSIGN(addr, addr);
 		__entry->key_type = key_type;
 		__entry->key_id = key_id;
-		memcpy(__entry->tsc, tsc, 6);
+		if (tsc)
+			memcpy(__entry->tsc, tsc, 6);
 	),
 	TP_printk(NETDEV_PR_FMT ", " MAC_PR_FMT ", key type: %d, key id: %d, tsc: %pm",
 		  NETDEV_PR_ARG, MAC_PR_ARG(addr), __entry->key_type,