mac80211: mlme: check for null after calling kmemdup

As the possible failure of the alloc, the ifmgd->assoc_req_ies might be
NULL pointer returned from kmemdup().
Therefore it might be better to free the skb and return error in order
to fail the association, like ieee80211_assoc_success().
Also, the caller, ieee80211_do_assoc(), needs to deal with the return
value from ieee80211_send_assoc().

Fixes: 4d9ec73d ("cfg80211: Report Association Request frame IEs in association events")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Link: https://lore.kernel.org/r/20220105081559.2387083-1-jiasheng@iscas.ac.cn
[fix some paths to be errors, not success]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/mlme.c

@@ -666,7 +666,7 @@ static void ieee80211_add_he_ie(struct ieee80211_sub_if_data *sdata,
 	ieee80211_ie_build_he_6ghz_cap(sdata, skb);
 }
 
-static void ieee80211_send_assoc(struct ieee80211_sub_if_data *sdata)
+static int ieee80211_send_assoc(struct ieee80211_sub_if_data *sdata)
 {
 	struct ieee80211_local *local = sdata->local;
 	struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
@@ -686,6 +686,7 @@ static void ieee80211_send_assoc(struct ieee80211_sub_if_data *sdata)
 	enum nl80211_iftype iftype = ieee80211_vif_type_p2p(&sdata->vif);
 	const struct ieee80211_sband_iftype_data *iftd;
 	struct ieee80211_prep_tx_info info = {};
+	int ret;
 
 	/* we know it's writable, cast away the const */
 	if (assoc_data->ie_len)
@@ -699,7 +700,7 @@ static void ieee80211_send_assoc(struct ieee80211_sub_if_data *sdata)
 	chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
 	if (WARN_ON(!chanctx_conf)) {
 		rcu_read_unlock();
-		return;
+		return -EINVAL;
 	}
 	chan = chanctx_conf->def.chan;
 	rcu_read_unlock();
@@ -750,7 +751,7 @@ static void ieee80211_send_assoc(struct ieee80211_sub_if_data *sdata)
 			(iftd ? iftd->vendor_elems.len : 0),
 			GFP_KERNEL);
 	if (!skb)
-		return;
+		return -ENOMEM;
 
 	skb_reserve(skb, local->hw.extra_tx_headroom);
 
@@ -1031,15 +1032,22 @@ static void ieee80211_send_assoc(struct ieee80211_sub_if_data *sdata)
 		skb_put_data(skb, assoc_data->ie + offset, noffset - offset);
 	}
 
-	if (assoc_data->fils_kek_len &&
-	    fils_encrypt_assoc_req(skb, assoc_data) < 0) {
-		dev_kfree_skb(skb);
-		return;
+	if (assoc_data->fils_kek_len) {
+		ret = fils_encrypt_assoc_req(skb, assoc_data);
+		if (ret < 0) {
+			dev_kfree_skb(skb);
+			return ret;
+		}
 	}
 
 	pos = skb_tail_pointer(skb);
 	kfree(ifmgd->assoc_req_ies);
 	ifmgd->assoc_req_ies = kmemdup(ie_start, pos - ie_start, GFP_ATOMIC);
+	if (!ifmgd->assoc_req_ies) {
+		dev_kfree_skb(skb);
+		return -ENOMEM;
+	}
+
 	ifmgd->assoc_req_ies_len = pos - ie_start;
 
 	drv_mgd_prepare_tx(local, sdata, &info);
@@ -1049,6 +1057,8 @@ static void ieee80211_send_assoc(struct ieee80211_sub_if_data *sdata)
 		IEEE80211_SKB_CB(skb)->flags |= IEEE80211_TX_CTL_REQ_TX_STATUS |
 						IEEE80211_TX_INTFL_MLME_CONN_TX;
 	ieee80211_tx_skb(sdata, skb);
+
+	return 0;
 }
 
 void ieee80211_send_pspoll(struct ieee80211_local *local,
@@ -4497,6 +4507,7 @@ static int ieee80211_do_assoc(struct ieee80211_sub_if_data *sdata)
 {
 	struct ieee80211_mgd_assoc_data *assoc_data = sdata->u.mgd.assoc_data;
 	struct ieee80211_local *local = sdata->local;
+	int ret;
 
 	sdata_assert_lock(sdata);
 
@@ -4517,7 +4528,9 @@ static int ieee80211_do_assoc(struct ieee80211_sub_if_data *sdata)
 	sdata_info(sdata, "associate with %pM (try %d/%d)\n",
 		   assoc_data->bss->bssid, assoc_data->tries,
 		   IEEE80211_ASSOC_MAX_TRIES);
-	ieee80211_send_assoc(sdata);
+	ret = ieee80211_send_assoc(sdata);
+	if (ret)
+		return ret;
 
 	if (!ieee80211_hw_check(&local->hw, REPORTS_TX_ACK_STATUS)) {
 		assoc_data->timeout = jiffies + IEEE80211_ASSOC_TIMEOUT;