[PATCH 5.15 056/317] wifi: wilc1000: fix RCU usage in connect path

Sasha Levin
2024-03-24T23:35:56Z

From: Alexis Lothoré <alexis.lothore@bootlin.com>

[ Upstream commit 205c50306acf58a335eb19fa84e40140f4fe814f ]

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
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/wireless/microchip/wilc1000/hif.c | 36 ++++++++++++-------
1 file changed, 24 insertions(+), 12 deletions(-)

diff --git a/drivers/net/wireless/microchip/wilc1000/hif.c b/drivers/net/wireless/microchip/wilc1000/hif.c
index edd51592a82da..fe95a6201a679 100644
--- a/drivers/net/wireless/microchip/wilc1000/hif.c
+++ b/drivers/net/wireless/microchip/wilc1000/hif.c
@@ -359,38 +359,49 @@ static void handle_connect_timeout(struct work_struct *work)
void *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)
@@ -401,7 +412,7 @@ void *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];

@@ -416,11 +427,11 @@ void *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) {
@@ -444,7 +455,7 @@ void *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;

@@ -459,13 +470,13 @@ void *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;
@@ -499,6 +510,7 @@ void *wilc_parse_join_bss_param(struct cfg80211_bss *bss,
param->akm_suites[i] = crypto->akm_suites[i] & 0xFF;
}

+ kfree(ies_data);
return (void *)param;
}

--
2.43.0