wifi: wilc1000: fix RCU usage in connect path

With lockdep enabled, calls to the connect function from cfg802.11 layer
lead to the following warning:

=============================
WARNING: suspicious RCU usage
6.7.0-rc1-wt+ #333 Not tainted
-----------------------------
drivers/net/wireless/microchip/wilc1000/hif.c:386
suspicious rcu_dereference_check() usage!
[...]
stack backtrace:
CPU: 0 PID: 100 Comm: wpa_supplicant Not tainted 6.7.0-rc1-wt+ #333
Hardware name: Atmel SAMA5
 unwind_backtrace from show_stack+0x18/0x1c
 show_stack from dump_stack_lvl+0x34/0x48
 dump_stack_lvl from wilc_parse_join_bss_param+0x7dc/0x7f4
 wilc_parse_join_bss_param from connect+0x2c4/0x648
 connect from cfg80211_connect+0x30c/0xb74
 cfg80211_connect from nl80211_connect+0x860/0xa94
 nl80211_connect from genl_rcv_msg+0x3fc/0x59c
 genl_rcv_msg from netlink_rcv_skb+0xd0/0x1f8
 netlink_rcv_skb from genl_rcv+0x2c/0x3c
 genl_rcv from netlink_unicast+0x3b0/0x550
 netlink_unicast from netlink_sendmsg+0x368/0x688
 netlink_sendmsg from ____sys_sendmsg+0x190/0x430
 ____sys_sendmsg from ___sys_sendmsg+0x110/0x158
 ___sys_sendmsg from sys_sendmsg+0xe8/0x150
 sys_sendmsg from ret_fast_syscall+0x0/0x1c

This warning is emitted because in the connect path, when trying to parse
target BSS parameters, we dereference a RCU pointer whithout being in RCU
critical section.
Fix RCU dereference usage by moving it to a RCU read critical section. To
avoid wrapping the whole wilc_parse_join_bss_param under the critical
section, just use the critical section to copy ies data

Fixes: c460495ee072 ("staging: wilc1000: fix incorrent type in initializer")
Signed-off-by: Alexis Lothoré <alexis.lothore@bootlin.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://msgid.link/20240105075733.36331-3-alexis.lothore@bootlin.com

diff --git a/drivers/net/wireless/microchip/wilc1000/hif.c b/drivers/net/wireless/microchip/wilc1000/hif.c
index 6f1218a510610c358e986ce775b818d2179dc65e..d2b8c26308198ac1c8c4702066bd7d0a298d0051 100644 (file)
--- a/drivers/net/wireless/microchip/wilc1000/hif.c
+++ b/drivers/net/wireless/microchip/wilc1000/hif.c
@@ -377,38 +377,49 @@ struct wilc_join_bss_param *
 wilc_parse_join_bss_param(struct cfg80211_bss *bss,
                          struct cfg80211_crypto_settings *crypto)
 {
-       const struct cfg80211_bss_ies *ies = rcu_dereference(bss->ies);
-       const u8 *tim_elm, *ssid_elm, *rates_ie, *supp_rates_ie;
+       const u8 *ies_data, *tim_elm, *ssid_elm, *rates_ie, *supp_rates_ie;
        const u8 *ht_ie, *wpa_ie, *wmm_ie, *rsn_ie;
        struct ieee80211_p2p_noa_attr noa_attr;
+       const struct cfg80211_bss_ies *ies;
        struct wilc_join_bss_param *param;
-       u8 rates_len = 0;
+       u8 rates_len = 0, ies_len;
        int ret;
 
        param = kzalloc(sizeof(*param), GFP_KERNEL);
        if (!param)
                return NULL;
 
+       rcu_read_lock();
+       ies = rcu_dereference(bss->ies);
+       ies_data = kmemdup(ies->data, ies->len, GFP_ATOMIC);
+       if (!ies_data) {
+               rcu_read_unlock();
+               kfree(param);
+               return NULL;
+       }
+       ies_len = ies->len;
+       rcu_read_unlock();
+
        param->beacon_period = cpu_to_le16(bss->beacon_interval);
        param->cap_info = cpu_to_le16(bss->capability);
        param->bss_type = WILC_FW_BSS_TYPE_INFRA;
        param->ch = ieee80211_frequency_to_channel(bss->channel->center_freq);
        ether_addr_copy(param->bssid, bss->bssid);
 
-       ssid_elm = cfg80211_find_ie(WLAN_EID_SSID, ies->data, ies->len);
+       ssid_elm = cfg80211_find_ie(WLAN_EID_SSID, ies_data, ies_len);
        if (ssid_elm) {
                if (ssid_elm[1] <= IEEE80211_MAX_SSID_LEN)
                        memcpy(param->ssid, ssid_elm + 2, ssid_elm[1]);
        }
 
-       tim_elm = cfg80211_find_ie(WLAN_EID_TIM, ies->data, ies->len);
+       tim_elm = cfg80211_find_ie(WLAN_EID_TIM, ies_data, ies_len);
        if (tim_elm && tim_elm[1] >= 2)
                param->dtim_period = tim_elm[3];
 
        memset(param->p_suites, 0xFF, 3);
        memset(param->akm_suites, 0xFF, 3);
 
-       rates_ie = cfg80211_find_ie(WLAN_EID_SUPP_RATES, ies->data, ies->len);
+       rates_ie = cfg80211_find_ie(WLAN_EID_SUPP_RATES, ies_data, ies_len);
        if (rates_ie) {
                rates_len = rates_ie[1];
                if (rates_len > WILC_MAX_RATES_SUPPORTED)
@@ -419,7 +430,7 @@ wilc_parse_join_bss_param(struct cfg80211_bss *bss,
 
        if (rates_len < WILC_MAX_RATES_SUPPORTED) {
                supp_rates_ie = cfg80211_find_ie(WLAN_EID_EXT_SUPP_RATES,
-                                                ies->data, ies->len);
+                                                ies_data, ies_len);
                if (supp_rates_ie) {
                        u8 ext_rates = supp_rates_ie[1];
 
@@ -434,11 +445,11 @@ wilc_parse_join_bss_param(struct cfg80211_bss *bss,
                }
        }
 
-       ht_ie = cfg80211_find_ie(WLAN_EID_HT_CAPABILITY, ies->data, ies->len);
+       ht_ie = cfg80211_find_ie(WLAN_EID_HT_CAPABILITY, ies_data, ies_len);
        if (ht_ie)
                param->ht_capable = true;
 
-       ret = cfg80211_get_p2p_attr(ies->data, ies->len,
+       ret = cfg80211_get_p2p_attr(ies_data, ies_len,
                                    IEEE80211_P2P_ATTR_ABSENCE_NOTICE,
                                    (u8 *)&noa_attr, sizeof(noa_attr));
        if (ret > 0) {
@@ -462,7 +473,7 @@ wilc_parse_join_bss_param(struct cfg80211_bss *bss,
        }
        wmm_ie = cfg80211_find_vendor_ie(WLAN_OUI_MICROSOFT,
                                         WLAN_OUI_TYPE_MICROSOFT_WMM,
-                                        ies->data, ies->len);
+                                        ies_data, ies_len);
        if (wmm_ie) {
                struct ieee80211_wmm_param_ie *ie;
 
@@ -477,13 +488,13 @@ wilc_parse_join_bss_param(struct cfg80211_bss *bss,
 
        wpa_ie = cfg80211_find_vendor_ie(WLAN_OUI_MICROSOFT,
                                         WLAN_OUI_TYPE_MICROSOFT_WPA,
-                                        ies->data, ies->len);
+                                        ies_data, ies_len);
        if (wpa_ie) {
                param->mode_802_11i = 1;
                param->rsn_found = true;
        }
 
-       rsn_ie = cfg80211_find_ie(WLAN_EID_RSN, ies->data, ies->len);
+       rsn_ie = cfg80211_find_ie(WLAN_EID_RSN, ies_data, ies_len);
        if (rsn_ie) {
                int rsn_ie_len = sizeof(struct element) + rsn_ie[1];
                int offset = 8;
@@ -517,6 +528,7 @@ wilc_parse_join_bss_param(struct cfg80211_bss *bss,
                        param->akm_suites[i] = crypto->akm_suites[i] & 0xFF;
        }
 
+       kfree(ies_data);
        return (void *)param;
 }