wifi: mac80211: apply mcast rate only if interface is up

If the interface isn't enabled, don't apply multicast
rate changes immediately.

Reported-by: syzbot+de87c09cc7b964ea2e23@syzkaller.appspotmail.com
Link: https://msgid.link/20240515133410.d6cffe5756cc.I47b624a317e62bdb4609ff7fa79403c0c444d32d@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/cfg.c

@@ -2958,8 +2958,9 @@ static int ieee80211_set_mcast_rate(struct wiphy *wiphy, struct net_device *dev,
 	memcpy(sdata->vif.bss_conf.mcast_rate, rate,
 	       sizeof(int) * NUM_NL80211_BANDS);
 
-	ieee80211_link_info_change_notify(sdata, &sdata->deflink,
-					  BSS_CHANGED_MCAST_RATE);
+	if (ieee80211_sdata_running(sdata))
+		ieee80211_link_info_change_notify(sdata, &sdata->deflink,
+						  BSS_CHANGED_MCAST_RATE);
 
 	return 0;
 }