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authorJohannes Berg <johannes.berg@intel.com>2012-11-29 01:25:20 +0100
committerJohannes Berg <johannes.berg@intel.com>2012-11-30 13:42:20 +0100
commit9caf03640279e64d0ba36539b42daa1b43a49486 (patch)
treecb094a4a577f61421d1b402e16f0e68f151d5726 /net/mac80211
parentb9a9ada14aab17f08c1d9735601f1097cdcfc6de (diff)
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>
Diffstat (limited to 'net/mac80211')
-rw-r--r--net/mac80211/mlme.c80
1 files changed, 49 insertions, 31 deletions
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 35d8cffc973..481d5035b39 100644
--- a/net/mac80211/mlme.c
+++ b/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);