[79/89] mac80211: fix IBSS teardown race

From: Greg KH
Date: Thu Jun 16 2011 - 03:04:34 EST

2.6.39-stable review patch. If anyone has any objections, please let us know.


From: Johannes Berg <johannes.berg@xxxxxxxxx>

commit f3209bea110cade12e2b133da8b8499689cb0e2e upstream.

Ignacy reports that sometimes after leaving an IBSS
joining a new one didn't work because there still
were stations on the list. He fixed it by flushing
stations when attempting to join a new IBSS, but
this shouldn't be happening in the first case. When
I looked into it I saw a race condition in teardown
that could cause stations to be added after flush,
and thus cause this situation. Ignacy confirms that
after applying my patch he hasn't seen this happen

Reported-by: Ignacy Gawedzki <i@xxxxxx>
Debugged-by: Ignacy Gawedzki <i@xxxxxx>
Tested-by: Ignacy Gawedzki <i@xxxxxx>
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
Signed-off-by: John W. Linville <linville@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

net/mac80211/ibss.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

--- a/net/mac80211/ibss.c
+++ b/net/mac80211/ibss.c
@@ -967,6 +967,10 @@ int ieee80211_ibss_leave(struct ieee8021


+ sdata->u.ibss.state = IEEE80211_IBSS_MLME_SEARCH;
+ memset(sdata->u.ibss.bssid, 0, ETH_ALEN);
+ sdata->u.ibss.ssid_len = 0;
active_ibss = ieee80211_sta_active_ibss(sdata);

if (!active_ibss && !is_zero_ether_addr(ifibss->bssid)) {
@@ -1000,8 +1004,6 @@ int ieee80211_ibss_leave(struct ieee8021

- memset(sdata->u.ibss.bssid, 0, ETH_ALEN);
- sdata->u.ibss.ssid_len = 0;


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