[PATCH] AP: Fix HT 20/40 co-ex transition timer cancellation on iface removal

[Martin Willi]

When removing an interface, hostapd_bss_deinit() frees all associated STAs.
If any of the stations is 40MHz intolerant, the cleanup invokes
ht40_intolerant_remove(), that in turn registers a 20->40MHz transition
timer for the last station. That timer is never canceled; once it executes,
the interface is gone, most likely resulting in a segfault when referencing
it.

While hostapd_interface_deinit() cancels the transition timer, it does so
before cleaning up STAs. Move the cancellation after STA cleanup to cancel
any timer that was registered during that operation.

Signed-off-by: Martin Willi <martin at strongswan.org>

---

I'm not sure if this is the correct/best place for this cancellation, given
that hostapd_bss_deinit() is called from other locations. This code path
is rather easy to hit when using the ctrl interface, though.
---
 src/ap/hostapd.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/src/ap/hostapd.c b/src/ap/hostapd.c
index d2eb0441c..05956461c 100644
--- a/src/ap/hostapd.c
+++ b/src/ap/hostapd.c
@@ -2191,12 +2191,6 @@ void hostapd_interface_deinit(struct hostapd_iface *iface)
 
 	hostapd_set_state(iface, HAPD_IFACE_DISABLED);
 
-#ifdef CONFIG_IEEE80211N
-#ifdef NEED_AP_MLME
-	hostapd_stop_setup_timers(iface);
-	eloop_cancel_timeout(ap_ht2040_timeout, iface, NULL);
-#endif /* NEED_AP_MLME */
-#endif /* CONFIG_IEEE80211N */
 	eloop_cancel_timeout(channel_list_update_timeout, iface, NULL);
 	iface->wait_channel_update = 0;
 
@@ -2212,6 +2206,13 @@ void hostapd_interface_deinit(struct hostapd_iface *iface)
 			break;
 		hostapd_bss_deinit(iface->bss[j]);
 	}
+
+#ifdef CONFIG_IEEE80211N
+#ifdef NEED_AP_MLME
+	hostapd_stop_setup_timers(iface);
+	eloop_cancel_timeout(ap_ht2040_timeout, iface, NULL);
+#endif /* NEED_AP_MLME */
+#endif /* CONFIG_IEEE80211N */
 }
 
 
-- 
2.14.1