nl80211: fix memory leak in nl80211_get_ftm_responder_stats

In nl80211_get_ftm_responder_stats, a new skb is created via nlmsg_new
named msg. If nl80211hdr_put() fails, then msg should be released. The
return statement should be replace by goto to error handling code.

Fixes: 81e54d0 ("cfg80211: support FTM responder configuration/statistics")
Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
Link: https://lore.kernel.org/r/20191004194220.19412-1-navid.emamdoost@gmail.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/nl80211.c

@@ -13682,7 +13682,7 @@ static int nl80211_get_ftm_responder_stats(struct sk_buff *skb,
 	hdr = nl80211hdr_put(msg, info->snd_portid, info->snd_seq, 0,
 			     NL80211_CMD_GET_FTM_RESPONDER_STATS);
 	if (!hdr)
-		return -ENOBUFS;
+		goto nla_put_failure;
 
 	if (nla_put_u32(msg, NL80211_ATTR_IFINDEX, dev->ifindex))
 		goto nla_put_failure;