cfg80211: fix BSS struct IE access races

When a BSS struct is updated, the IEs are currently
overwritten or freed. This can lead to races if some
other CPU is accessing the BSS struct and using the
IEs concurrently.

Fix this by always allocating the IEs in a new struct
that holds the data and length and protecting access
to this new struct with RCU.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/libertas/cfg.c

@@ -298,6 +298,7 @@ static int lbs_add_common_rates_tlv(u8 *tlv, struct cfg80211_bss *bss)
 	const u8 *rates_eid, *ext_rates_eid;
 	int n = 0;
 
+	rcu_read_lock();
 	rates_eid = ieee80211_bss_get_ie(bss, WLAN_EID_SUPP_RATES);
 	ext_rates_eid = ieee80211_bss_get_ie(bss, WLAN_EID_EXT_SUPP_RATES);
 
@@ -325,6 +326,7 @@ static int lbs_add_common_rates_tlv(u8 *tlv, struct cfg80211_bss *bss)
 		*tlv++ = 0x96;
 		n = 4;
 	}
+	rcu_read_unlock();
 
 	rate_tlv->header.len = cpu_to_le16(n);
 	return sizeof(rate_tlv->header) + n;
@@ -1140,11 +1142,13 @@ static int lbs_associate(struct lbs_private *priv,
 	cmd->capability = cpu_to_le16(bss->capability);
 
 	/* add SSID TLV */
+	rcu_read_lock();
 	ssid_eid = ieee80211_bss_get_ie(bss, WLAN_EID_SSID);
 	if (ssid_eid)
 		pos += lbs_add_ssid_tlv(pos, ssid_eid + 2, ssid_eid[1]);
 	else
 		lbs_deb_assoc("no SSID\n");
+	rcu_read_unlock();
 
 	/* add DS param TLV */
 	if (bss->channel)
@@ -1782,7 +1786,7 @@ static int lbs_ibss_join_existing(struct lbs_private *priv,
 	struct cfg80211_ibss_params *params,
 	struct cfg80211_bss *bss)
 {
-	const u8 *rates_eid = ieee80211_bss_get_ie(bss, WLAN_EID_SUPP_RATES);
+	const u8 *rates_eid;
 	struct cmd_ds_802_11_ad_hoc_join cmd;
 	u8 preamble = RADIO_PREAMBLE_SHORT;
 	int ret = 0;
@@ -1841,6 +1845,8 @@ static int lbs_ibss_join_existing(struct lbs_private *priv,
 
 	/* set rates to the intersection of our rates and the rates in the
 	   bss */
+	rcu_read_lock();
+	rates_eid = ieee80211_bss_get_ie(bss, WLAN_EID_SUPP_RATES);
 	if (!rates_eid) {
 		lbs_add_rates(cmd.bss.rates);
 	} else {
@@ -1860,6 +1866,7 @@ static int lbs_ibss_join_existing(struct lbs_private *priv,
 			}
 		}
 	}
+	rcu_read_unlock();
 
 	/* Only v8 and below support setting this */
 	if (MRVL_FW_MAJOR_REV(priv->fwrelease) <= 8) {

drivers/net/wireless/mwifiex/sta_ioctl.c

@@ -158,12 +158,22 @@ int mwifiex_fill_new_bss_desc(struct mwifiex_private *priv,
 			      struct cfg80211_bss *bss,
 			      struct mwifiex_bssdescriptor *bss_desc)
 {
-	int ret;
+	int ret, beacon_ie_len;
 	u8 *beacon_ie;
 	struct mwifiex_bss_priv *bss_priv = (void *)bss->priv;
+	const struct cfg80211_bss_ies *ies;
+
+	rcu_read_lock();
+	ies = rcu_dereference(bss->ies);
+	if (WARN_ON(!ies)) {
+		/* should never happen */
+		rcu_read_unlock();
+		return -EINVAL;
+	}
+	beacon_ie = kmemdup(ies->data, ies->len, GFP_ATOMIC);
+	beacon_ie_len = ies->len;
+	rcu_read_unlock();
 
-	beacon_ie = kmemdup(bss->information_elements, bss->len_beacon_ies,
-			    GFP_KERNEL);
 	if (!beacon_ie) {
 		dev_err(priv->adapter->dev, " failed to alloc beacon_ie\n");
 		return -ENOMEM;
@@ -172,7 +182,7 @@ int mwifiex_fill_new_bss_desc(struct mwifiex_private *priv,
 	memcpy(bss_desc->mac_address, bss->bssid, ETH_ALEN);
 	bss_desc->rssi = bss->signal;
 	bss_desc->beacon_buf = beacon_ie;
-	bss_desc->beacon_buf_size = bss->len_beacon_ies;
+	bss_desc->beacon_buf_size = beacon_ie_len;
 	bss_desc->beacon_period = bss->beacon_interval;
 	bss_desc->cap_info_bitmap = bss->capability;
 	bss_desc->bss_band = bss_priv->band;
@@ -198,18 +208,23 @@ int mwifiex_fill_new_bss_desc(struct mwifiex_private *priv,
 static int mwifiex_process_country_ie(struct mwifiex_private *priv,
 				      struct cfg80211_bss *bss)
 {
-	u8 *country_ie, country_ie_len;
+	const u8 *country_ie;
+	u8 country_ie_len;
 	struct mwifiex_802_11d_domain_reg *domain_info =
 					&priv->adapter->domain_reg;
 
-	country_ie = (u8 *)ieee80211_bss_get_ie(bss, WLAN_EID_COUNTRY);
-
-	if (!country_ie)
+	rcu_read_lock();
+	country_ie = ieee80211_bss_get_ie(bss, WLAN_EID_COUNTRY);
+	if (!country_ie) {
+		rcu_read_unlock();
 		return 0;
+	}
 
 	country_ie_len = country_ie[1];
-	if (country_ie_len < IEEE80211_COUNTRY_IE_MIN_LEN)
+	if (country_ie_len < IEEE80211_COUNTRY_IE_MIN_LEN) {
+		rcu_read_unlock();
 		return 0;
+	}
 
 	domain_info->country_code[0] = country_ie[2];
 	domain_info->country_code[1] = country_ie[3];
@@ -223,6 +238,8 @@ static int mwifiex_process_country_ie(struct mwifiex_private *priv,
 	memcpy((u8 *)domain_info->triplet,
 	       &country_ie[2] + IEEE80211_COUNTRY_STRING_LEN, country_ie_len);
 
+	rcu_read_unlock();
+
 	if (mwifiex_send_cmd_async(priv, HostCmd_CMD_802_11D_DOMAIN_INFO,
 				   HostCmd_ACT_GEN_SET, 0, NULL)) {
 		wiphy_err(priv->adapter->wiphy,

include/net/cfg80211.h

@@ -1205,6 +1205,18 @@ enum cfg80211_signal_type {
 	CFG80211_SIGNAL_TYPE_UNSPEC,
 };
 
+/**
+ * struct cfg80211_bss_ie_data - BSS entry IE data
+ * @rcu_head: internal use, for freeing
+ * @len: length of the IEs
+ * @data: IE data
+ */
+struct cfg80211_bss_ies {
+	struct rcu_head rcu_head;
+	int len;
+	u8 data[];
+};
+
 /**
  * struct cfg80211_bss - BSS description
  *
@@ -1216,36 +1228,34 @@ enum cfg80211_signal_type {
  * @tsf: timestamp of last received update
  * @beacon_interval: the beacon interval as from the frame
  * @capability: the capability field in host byte order
- * @information_elements: the information elements (Note that there
+ * @ies: the information elements (Note that there
  *	is no guarantee that these are well-formed!); this is a pointer to
  *	either the beacon_ies or proberesp_ies depending on whether Probe
  *	Response frame has been received
- * @len_information_elements: total length of the information elements
  * @beacon_ies: the information elements from the last Beacon frame
- * @len_beacon_ies: total length of the beacon_ies
  * @proberesp_ies: the information elements from the last Probe Response frame
- * @len_proberesp_ies: total length of the proberesp_ies
  * @signal: signal strength value (type depends on the wiphy's signal_type)
  * @free_priv: function pointer to free private data
  * @priv: private area for driver use, has at least wiphy->bss_priv_size bytes
  */
 struct cfg80211_bss {
+	u64 tsf;
+
 	struct ieee80211_channel *channel;
 
-	u8 bssid[ETH_ALEN];
-	u64 tsf;
+	const struct cfg80211_bss_ies __rcu *ies;
+	const struct cfg80211_bss_ies __rcu *beacon_ies;
+	const struct cfg80211_bss_ies __rcu *proberesp_ies;
+
+	void (*free_priv)(struct cfg80211_bss *bss);
+
+	s32 signal;
+
 	u16 beacon_interval;
 	u16 capability;
-	u8 *information_elements;
-	size_t len_information_elements;
-	u8 *beacon_ies;
-	size_t len_beacon_ies;
-	u8 *proberesp_ies;
-	size_t len_proberesp_ies;
 
-	s32 signal;
+	u8 bssid[ETH_ALEN];
 
-	void (*free_priv)(struct cfg80211_bss *bss);
 	u8 priv[0] __attribute__((__aligned__(sizeof(void *))));
 };
 
@@ -1253,6 +1263,9 @@ struct cfg80211_bss {
  * ieee80211_bss_get_ie - find IE with given ID
  * @bss: the bss to search
  * @ie: the IE ID
+ *
+ * Note that the return value is an RCU-protected pointer, so
+ * rcu_read_lock() must be held when calling this function.
  * Returns %NULL if not found.
  */
 const u8 *ieee80211_bss_get_ie(struct cfg80211_bss *bss, u8 ie);

net/mac80211/mlme.c

@@ -1382,19 +1382,26 @@ static void ieee80211_set_associated(struct ieee80211_sub_if_data *sdata,
 	sdata->u.mgd.flags |= IEEE80211_STA_RESET_SIGNAL_AVE;
 
 	if (sdata->vif.p2p) {
-		u8 noa[2];
-		int ret;
+		const struct cfg80211_bss_ies *ies;
 
-		ret = cfg80211_get_p2p_attr(cbss->information_elements,
-					    cbss->len_information_elements,
-					    IEEE80211_P2P_ATTR_ABSENCE_NOTICE,
-					    noa, sizeof(noa));
-		if (ret >= 2) {
-			bss_conf->p2p_oppps = noa[1] & 0x80;
-			bss_conf->p2p_ctwindow = noa[1] & 0x7f;
-			bss_info_changed |= BSS_CHANGED_P2P_PS;
-			sdata->u.mgd.p2p_noa_index = noa[0];
+		rcu_read_lock();
+		ies = rcu_dereference(cbss->ies);
+		if (ies) {
+			u8 noa[2];
+			int ret;
+
+			ret = cfg80211_get_p2p_attr(
+					ies->data, ies->len,
+					IEEE80211_P2P_ATTR_ABSENCE_NOTICE,
+					noa, sizeof(noa));
+			if (ret >= 2) {
+				bss_conf->p2p_oppps = noa[1] & 0x80;
+				bss_conf->p2p_ctwindow = noa[1] & 0x7f;
+				bss_info_changed |= BSS_CHANGED_P2P_PS;
+				sdata->u.mgd.p2p_noa_index = noa[0];
+			}
 		}
+		rcu_read_unlock();
 	}
 
 	/* just to be sure */
@@ -1659,6 +1666,7 @@ static void ieee80211_mgd_probe_ap_send(struct ieee80211_sub_if_data *sdata)
 	} else {
 		int ssid_len;
 
+		rcu_read_lock();
 		ssid = ieee80211_bss_get_ie(ifmgd->associated, WLAN_EID_SSID);
 		if (WARN_ON_ONCE(ssid == NULL))
 			ssid_len = 0;
@@ -1668,6 +1676,7 @@ static void ieee80211_mgd_probe_ap_send(struct ieee80211_sub_if_data *sdata)
 		ieee80211_send_probe_req(sdata, dst, ssid + 2, ssid_len, NULL,
 					 0, (u32) -1, true, false,
 					 ifmgd->associated->channel, false);
+		rcu_read_unlock();
 	}
 
 	ifmgd->probe_timeout = jiffies + msecs_to_jiffies(probe_wait_ms);
@@ -1763,6 +1772,7 @@ struct sk_buff *ieee80211_ap_probereq_get(struct ieee80211_hw *hw,
 	else
 		return NULL;
 
+	rcu_read_lock();
 	ssid = ieee80211_bss_get_ie(cbss, WLAN_EID_SSID);
 	if (WARN_ON_ONCE(ssid == NULL))
 		ssid_len = 0;
@@ -1773,6 +1783,7 @@ struct sk_buff *ieee80211_ap_probereq_get(struct ieee80211_hw *hw,
 					(u32) -1, cbss->channel,
 					ssid + 2, ssid_len,
 					NULL, 0, true);
+	rcu_read_unlock();
 
 	return skb;
 }
@@ -2858,9 +2869,12 @@ static int ieee80211_probe_auth(struct ieee80211_sub_if_data *sdata)
 			   auth_data->bss->bssid, auth_data->tries,
 			   IEEE80211_AUTH_MAX_TRIES);
 
+		rcu_read_lock();
 		ssidie = ieee80211_bss_get_ie(auth_data->bss, WLAN_EID_SSID);
-		if (!ssidie)
+		if (!ssidie) {
+			rcu_read_unlock();
 			return -EINVAL;
+		}
 		/*
 		 * Direct probe is sent to broadcast address as some APs
 		 * will not answer to direct packet in unassociated state.
@@ -2868,6 +2882,7 @@ static int ieee80211_probe_auth(struct ieee80211_sub_if_data *sdata)
 		ieee80211_send_probe_req(sdata, NULL, ssidie + 2, ssidie[1],
 					 NULL, 0, (u32) -1, true, false,
 					 auth_data->bss->channel, false);
+		rcu_read_unlock();
 	}
 
 	auth_data->timeout = jiffies + IEEE80211_AUTH_TIMEOUT;
@@ -3404,9 +3419,7 @@ static u8 ieee80211_ht_vht_rx_chains(struct ieee80211_sub_if_data *sdata,
 	if (ifmgd->flags & IEEE80211_STA_DISABLE_HT)
 		return chains;
 
-	ht_cap_ie = cfg80211_find_ie(WLAN_EID_HT_CAPABILITY,
-				     cbss->information_elements,
-				     cbss->len_information_elements);
+	ht_cap_ie = ieee80211_bss_get_ie(cbss, WLAN_EID_HT_CAPABILITY);
 	if (ht_cap_ie && ht_cap_ie[1] >= sizeof(*ht_cap)) {
 		ht_cap = (void *)(ht_cap_ie + 2);
 		chains = ieee80211_mcs_to_chains(&ht_cap->mcs);
@@ -3419,9 +3432,7 @@ static u8 ieee80211_ht_vht_rx_chains(struct ieee80211_sub_if_data *sdata,
 	if (ifmgd->flags & IEEE80211_STA_DISABLE_VHT)
 		return chains;
 
-	vht_cap_ie = cfg80211_find_ie(WLAN_EID_VHT_CAPABILITY,
-				      cbss->information_elements,
-				      cbss->len_information_elements);
+	vht_cap_ie = ieee80211_bss_get_ie(cbss, WLAN_EID_VHT_CAPABILITY);
 	if (vht_cap_ie && vht_cap_ie[1] >= sizeof(*vht_cap)) {
 		u8 nss;
 		u16 tx_mcs_map;
@@ -3457,13 +3468,13 @@ static int ieee80211_prep_channel(struct ieee80211_sub_if_data *sdata,
 			  IEEE80211_STA_DISABLE_80P80MHZ |
 			  IEEE80211_STA_DISABLE_160MHZ);
 
+	rcu_read_lock();
+
 	if (!(ifmgd->flags & IEEE80211_STA_DISABLE_HT) &&
 	    sband->ht_cap.ht_supported) {
 		const u8 *ht_oper_ie;
 
-		ht_oper_ie = cfg80211_find_ie(WLAN_EID_HT_OPERATION,
-					      cbss->information_elements,
-					      cbss->len_information_elements);
+		ht_oper_ie = ieee80211_bss_get_ie(cbss, WLAN_EID_HT_OPERATION);
 		if (ht_oper_ie && ht_oper_ie[1] >= sizeof(*ht_oper))
 			ht_oper = (void *)(ht_oper_ie + 2);
 	}
@@ -3472,9 +3483,8 @@ static int ieee80211_prep_channel(struct ieee80211_sub_if_data *sdata,
 	    sband->vht_cap.vht_supported) {
 		const u8 *vht_oper_ie;
 
-		vht_oper_ie = cfg80211_find_ie(WLAN_EID_VHT_OPERATION,
-					       cbss->information_elements,
-					       cbss->len_information_elements);
+		vht_oper_ie = ieee80211_bss_get_ie(cbss,
+						   WLAN_EID_VHT_OPERATION);
 		if (vht_oper_ie && vht_oper_ie[1] >= sizeof(*vht_oper))
 			vht_oper = (void *)(vht_oper_ie + 2);
 		if (vht_oper && !ht_oper) {
@@ -3494,6 +3504,8 @@ static int ieee80211_prep_channel(struct ieee80211_sub_if_data *sdata,
 	sdata->needed_rx_chains = min(ieee80211_ht_vht_rx_chains(sdata, cbss),
 				      local->rx_chains);
 
+	rcu_read_unlock();
+
 	/* will change later if needed */
 	sdata->smps_mode = IEEE80211_SMPS_OFF;
 
@@ -3734,14 +3746,21 @@ int ieee80211_mgd_assoc(struct ieee80211_sub_if_data *sdata,
 	const u8 *ssidie, *ht_ie;
 	int i, err;
 
-	ssidie = ieee80211_bss_get_ie(req->bss, WLAN_EID_SSID);
-	if (!ssidie)
-		return -EINVAL;
-
 	assoc_data = kzalloc(sizeof(*assoc_data) + req->ie_len, GFP_KERNEL);
 	if (!assoc_data)
 		return -ENOMEM;
 
+	rcu_read_lock();
+	ssidie = ieee80211_bss_get_ie(req->bss, WLAN_EID_SSID);
+	if (!ssidie) {
+		rcu_read_unlock();
+		kfree(assoc_data);
+		return -EINVAL;
+	}
+	memcpy(assoc_data->ssid, ssidie + 2, ssidie[1]);
+	assoc_data->ssid_len = ssidie[1];
+	rcu_read_unlock();
+
 	mutex_lock(&ifmgd->mtx);
 
 	if (ifmgd->associated)
@@ -3836,12 +3855,14 @@ int ieee80211_mgd_assoc(struct ieee80211_sub_if_data *sdata,
 	assoc_data->supp_rates = bss->supp_rates;
 	assoc_data->supp_rates_len = bss->supp_rates_len;
 
+	rcu_read_lock();
 	ht_ie = ieee80211_bss_get_ie(req->bss, WLAN_EID_HT_OPERATION);
 	if (ht_ie && ht_ie[1] >= sizeof(struct ieee80211_ht_operation))
 		assoc_data->ap_ht_param =
 			((struct ieee80211_ht_operation *)(ht_ie + 2))->ht_param;
 	else
 		ifmgd->flags |= IEEE80211_STA_DISABLE_HT;
+	rcu_read_unlock();
 
 	if (bss->wmm_used && bss->uapsd_supported &&
 	    (sdata->local->hw.flags & IEEE80211_HW_SUPPORTS_UAPSD)) {
@@ -3852,9 +3873,6 @@ int ieee80211_mgd_assoc(struct ieee80211_sub_if_data *sdata,
 		ifmgd->flags &= ~IEEE80211_STA_UAPSD_ENABLED;
 	}
 
-	memcpy(assoc_data->ssid, ssidie + 2, ssidie[1]);
-	assoc_data->ssid_len = ssidie[1];
-
 	if (req->prev_bssid)
 		memcpy(assoc_data->prev_bssid, req->prev_bssid, ETH_ALEN);
 

net/wireless/core.h

@@ -138,8 +138,6 @@ struct cfg80211_internal_bss {
 	unsigned long ts;
 	struct kref ref;
 	atomic_t hold;
-	bool beacon_ies_allocated;
-	bool proberesp_ies_allocated;
 
 	/* must be last because of priv member */
 	struct cfg80211_bss pub;

net/wireless/nl80211.c

@@ -4808,6 +4808,7 @@ static int nl80211_send_bss(struct sk_buff *msg, struct netlink_callback *cb,
 			    struct cfg80211_internal_bss *intbss)
 {
 	struct cfg80211_bss *res = &intbss->pub;
+	const struct cfg80211_bss_ies *ies;
 	void *hdr;
 	struct nlattr *bss;
 
@@ -4828,16 +4829,24 @@ static int nl80211_send_bss(struct sk_buff *msg, struct netlink_callback *cb,
 	if (!bss)
 		goto nla_put_failure;
 	if ((!is_zero_ether_addr(res->bssid) &&
-	     nla_put(msg, NL80211_BSS_BSSID, ETH_ALEN, res->bssid)) ||
-	    (res->information_elements && res->len_information_elements &&
-	     nla_put(msg, NL80211_BSS_INFORMATION_ELEMENTS,
-		     res->len_information_elements,
-		     res->information_elements)) ||
-	    (res->beacon_ies && res->len_beacon_ies &&
-	     res->beacon_ies != res->information_elements &&
-	     nla_put(msg, NL80211_BSS_BEACON_IES,
-		     res->len_beacon_ies, res->beacon_ies)))
+	     nla_put(msg, NL80211_BSS_BSSID, ETH_ALEN, res->bssid)))
 		goto nla_put_failure;
+
+	rcu_read_lock();
+	ies = rcu_dereference(res->ies);
+	if (ies && ies->len && nla_put(msg, NL80211_BSS_INFORMATION_ELEMENTS,
+				       ies->len, ies->data)) {
+		rcu_read_unlock();
+		goto nla_put_failure;
+	}
+	ies = rcu_dereference(res->beacon_ies);
+	if (ies && ies->len && nla_put(msg, NL80211_BSS_BEACON_IES,
+				       ies->len, ies->data)) {
+		rcu_read_unlock();
+		goto nla_put_failure;
+	}
+	rcu_read_unlock();
+
 	if (res->tsf &&
 	    nla_put_u64(msg, NL80211_BSS_TSF, res->tsf))
 		goto nla_put_failure;

net/wireless/reg.c

@@ -1797,7 +1797,7 @@ EXPORT_SYMBOL(regulatory_hint);
  */
 void regulatory_hint_11d(struct wiphy *wiphy,
 			 enum ieee80211_band band,
-			 u8 *country_ie,
+			 const u8 *country_ie,
 			 u8 country_ie_len)
 {
 	char alpha2[2];

net/wireless/reg.h

@@ -81,7 +81,7 @@ int regulatory_hint_found_beacon(struct wiphy *wiphy,
  */
 void regulatory_hint_11d(struct wiphy *wiphy,
 			 enum ieee80211_band band,
-			 u8 *country_ie,
+			 const u8 *country_ie,
 			 u8 country_ie_len);
 
 /**

net/wireless/sme.c

@@ -417,7 +417,7 @@ void __cfg80211_connect_result(struct net_device *dev, const u8 *bssid,
 			       struct cfg80211_bss *bss)
 {
 	struct wireless_dev *wdev = dev->ieee80211_ptr;
-	u8 *country_ie;
+	const u8 *country_ie;
 #ifdef CONFIG_CFG80211_WEXT
 	union iwreq_data wrqu;
 #endif
@@ -501,7 +501,15 @@ void __cfg80211_connect_result(struct net_device *dev, const u8 *bssid,
 	wdev->sme_state = CFG80211_SME_CONNECTED;
 	cfg80211_upload_connect_keys(wdev);
 
-	country_ie = (u8 *) ieee80211_bss_get_ie(bss, WLAN_EID_COUNTRY);
+	rcu_read_lock();
+	country_ie = ieee80211_bss_get_ie(bss, WLAN_EID_COUNTRY);
+	if (!country_ie) {
+		rcu_read_unlock();
+		return;
+	}
+
+	country_ie = kmemdup(country_ie, 2 + country_ie[1], GFP_ATOMIC);
+	rcu_read_unlock();
 
 	if (!country_ie)
 		return;
@@ -515,6 +523,7 @@ void __cfg80211_connect_result(struct net_device *dev, const u8 *bssid,
 			    bss->channel->band,
 			    country_ie + 2,
 			    country_ie[1]);
+	kfree(country_ie);
 }
 
 void cfg80211_connect_result(struct net_device *dev, const u8 *bssid,

net/wireless/util.c

@@ -688,10 +688,13 @@ EXPORT_SYMBOL(cfg80211_classify8021d);
 
 const u8 *ieee80211_bss_get_ie(struct cfg80211_bss *bss, u8 ie)
 {
-	if (bss->information_elements == NULL)
+	const struct cfg80211_bss_ies *ies;
+
+	ies = rcu_dereference(bss->ies);
+	if (!ies)
 		return NULL;
-	return cfg80211_find_ie(ie, bss->information_elements,
-				 bss->len_information_elements);
+
+	return cfg80211_find_ie(ie, ies->data, ies->len);
 }
 EXPORT_SYMBOL(ieee80211_bss_get_ie);
 

net/wireless/wext-sme.c

@@ -242,13 +242,17 @@ int cfg80211_mgd_wext_giwessid(struct net_device *dev,
 
 	wdev_lock(wdev);
 	if (wdev->current_bss) {
-		const u8 *ie = ieee80211_bss_get_ie(&wdev->current_bss->pub,
-						    WLAN_EID_SSID);
+		const u8 *ie;
+
+		rcu_read_lock();
+		ie = ieee80211_bss_get_ie(&wdev->current_bss->pub,
+					  WLAN_EID_SSID);
 		if (ie) {
 			data->flags = 1;
 			data->length = ie[1];
 			memcpy(ssid, ie + 2, data->length);
 		}
+		rcu_read_unlock();
 	} else if (wdev->wext.connect.ssid && wdev->wext.connect.ssid_len) {
 		data->flags = 1;
 		data->length = wdev->wext.connect.ssid_len;