mac80211: fix various problems in ibss code
There are a few problems in the IBSS code:
a) it tries to activate interfaces that are down after scanning
b) it crashes after scanning on an IBSS iface that isn't active
c) since the ssid_len is used as a flag, need to make it visible
only after all other settings are set, this helps protect
against b)
For b), we get a system crash:
wlan0: Creating new IBSS network, BSSID ce:f9:88:76:1e:4d
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<...>] ieee80211_sta_find_ibss+0x294/0x37d [mac80211]
Call Trace:
[<...>] ieee80211_ibss_notify_scan_completed+0x0/0x88 [mac80211]
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/ibss.c b/net/mac80211/ibss.c
index 6030e00..895f485 100644
--- a/net/mac80211/ibss.c
+++ b/net/mac80211/ibss.c
@@ -786,8 +786,12 @@
mutex_lock(&local->iflist_mtx);
list_for_each_entry(sdata, &local->interfaces, list) {
+ if (!netif_running(sdata->dev))
+ continue;
if (sdata->vif.type != NL80211_IFTYPE_ADHOC)
continue;
+ if (!sdata->u.ibss.ssid_len)
+ continue;
sdata->u.ibss.last_scan_completed = jiffies;
ieee80211_sta_find_ibss(sdata);
}
@@ -827,9 +831,6 @@
{
struct sk_buff *skb;
- memcpy(sdata->u.ibss.ssid, params->ssid, IEEE80211_MAX_SSID_LEN);
- sdata->u.ibss.ssid_len = params->ssid_len;
-
if (params->bssid) {
memcpy(sdata->u.ibss.bssid, params->bssid, ETH_ALEN);
sdata->u.ibss.fixed_bssid = true;
@@ -859,6 +860,17 @@
sdata->u.ibss.state = IEEE80211_IBSS_MLME_SEARCH;
sdata->u.ibss.ibss_join_req = jiffies;
+ memcpy(sdata->u.ibss.ssid, params->ssid, IEEE80211_MAX_SSID_LEN);
+
+ /*
+ * The ssid_len setting below is used to see whether
+ * we are active, and we need all other settings
+ * before that may get visible.
+ */
+ mb();
+
+ sdata->u.ibss.ssid_len = params->ssid_len;
+
set_bit(IEEE80211_IBSS_REQ_RUN, &sdata->u.ibss.request);
queue_work(sdata->local->hw.workqueue, &sdata->u.ibss.work);