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mac80211: fix scan vs. interface removal race

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When we remove an interface, we can currently end up having
a pointer to it left in local->scan_sdata after it has been
set down, and then with a hardware scan the scan completion
can try to access it which is a bug. Alternatively, a scan
that started as a hardware scan may terminate as though it
was a software scan, if the timing is just right.

On SMP systems, software scan also has a similar problem,
just canceling the delayed work and setting a flag isn't
enough since it may be running concurrently; in this case
we would also never restore state of other interfaces.

This patch hopefully fixes the problems by always invoking
ieee80211_scan_completed or requiring it to be invoked by
the driver, I suspect the drivers that have ->hw_scan() are
buggy. The bug will not manifest itself unless you remove
the interface while hw-scanning which will also turn off
the hw, and then add a new interface which will be unusable
until you scan once.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Johannes Berg
2008-09-11 00:01:51 +02:00
committed by John W. Linville
parent b7413430d4
commit 5bc75728fd
4 changed files with 56 additions and 21 deletions
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2
net/mac80211/mlme.c
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@@ -2530,7 +2530,7 @@ void ieee80211_mlme_notify_scan_completed(struct ieee80211_local *local)
struct ieee80211_sub_if_data *sdata = local->scan_sdata;
struct ieee80211_if_sta *ifsta;
if (sdata->vif.type == IEEE80211_IF_TYPE_IBSS) {
if (sdata && sdata->vif.type == IEEE80211_IF_TYPE_IBSS) {
ifsta = &sdata->u.sta;
if (!(ifsta->flags & IEEE80211_STA_BSSID_SET) ||
(!(ifsta->state == IEEE80211_STA_MLME_IBSS_JOINED) &&