Commit 4c4d684a authored Dec 04, 2013 by Ujjal Roy Committed by Johannes Berg Dec 05, 2013

cfg80211: fix WARN_ON for re-association to the expired BSS



cfg80211 allows re-association in managed mode and if a user
wants to re-associate to the same AP network after the time
period of IEEE80211_SCAN_RESULT_EXPIRE, cfg80211 warns with
the following message on receiving the connect result event.

------------[ cut here ]------------
WARNING: CPU: 0 PID: 13984 at net/wireless/sme.c:658
         __cfg80211_connect_result+0x3a6/0x3e0 [cfg80211]()
Call Trace:
 [<ffffffff81747a41>] dump_stack+0x46/0x58
 [<ffffffff81045847>] warn_slowpath_common+0x87/0xb0
 [<ffffffff81045885>] warn_slowpath_null+0x15/0x20
 [<ffffffffa05345f6>] __cfg80211_connect_result+0x3a6/0x3e0 [cfg80211]
 [<ffffffff8107168b>] ? update_rq_clock+0x2b/0x50
 [<ffffffff81078c01>] ? update_curr+0x1/0x160
 [<ffffffffa05133d2>] cfg80211_process_wdev_events+0xb2/0x1c0 [cfg80211]
 [<ffffffff81079303>] ? pick_next_task_fair+0x63/0x170
 [<ffffffffa0513518>] cfg80211_process_rdev_events+0x38/0x90 [cfg80211]
 [<ffffffffa050f03d>] cfg80211_event_work+0x1d/0x30 [cfg80211]
 [<ffffffff8105f21f>] process_one_work+0x17f/0x420
 [<ffffffff8105f90a>] worker_thread+0x11a/0x370
 [<ffffffff8105f7f0>] ? rescuer_thread+0x2f0/0x2f0
 [<ffffffff8106638b>] kthread+0xbb/0xc0
 [<ffffffff810662d0>] ? kthread_create_on_node+0x120/0x120
 [<ffffffff817574bc>] ret_from_fork+0x7c/0xb0
 [<ffffffff810662d0>] ? kthread_create_on_node+0x120/0x120
---[ end trace 61f3bddc9c4981f7 ]---

The reason is that, in connect result event cfg80211 unholds
the BSS to which the device is associated (and was held so
far). So, for the event with status successful, when cfg80211
wants to get that BSS from the device's BSS list it gets a
NULL BSS because the BSS has been expired and unheld already.

Fix it by reshuffling the code.

Signed-off-by: Ujjal Roy <royujjal@gmail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

parent 0834ae3c

net/wireless/sme.c

+12 −10

Original line number	Diff line number	Diff line
		@@ -632,6 +632,16 @@ void __cfg80211_connect_result(struct net_device dev, const u8 bssid,
		}
		#endif

		if (!bss && (status == WLAN_STATUS_SUCCESS)) {
		WARN_ON_ONCE(!wiphy_to_dev(wdev->wiphy)->ops->connect);
		bss = cfg80211_get_bss(wdev->wiphy, NULL, bssid,
		wdev->ssid, wdev->ssid_len,
		WLAN_CAPABILITY_ESS,
		WLAN_CAPABILITY_ESS);
		if (bss)
		cfg80211_hold_bss(bss_from_pub(bss));
		}

		if (wdev->current_bss) {
		cfg80211_unhold_bss(wdev->current_bss);
		cfg80211_put_bss(wdev->wiphy, &wdev->current_bss->pub);
		@@ -649,16 +659,8 @@ void __cfg80211_connect_result(struct net_device dev, const u8 bssid,
		return;
		}

		if (!bss) {
		WARN_ON_ONCE(!wiphy_to_dev(wdev->wiphy)->ops->connect);
		bss = cfg80211_get_bss(wdev->wiphy, NULL, bssid,
		wdev->ssid, wdev->ssid_len,
		WLAN_CAPABILITY_ESS,
		WLAN_CAPABILITY_ESS);
		if (WARN_ON(!bss))
		return;
		cfg80211_hold_bss(bss_from_pub(bss));
		}

		wdev->current_bss = bss_from_pub(bss);

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