[PATCH 4.9 20/23] cfg80211: fix connect/disconnect edge cases

From: Greg Kroah-Hartman
Date: Tue Oct 31 2017 - 06:14:04 EST


4.9-stable review patch. If anyone has any objections, please let me know.

------------------

From: Johannes Berg <johannes.berg@xxxxxxxxx>

commit 51e13359cd5ea34acc62c90627603352956380af upstream.

If we try to connect while already connected/connecting, but
this fails, we set ssid_len=0 but leave current_bss hanging,
leading to errors.

Check all of this better, first of all ensuring that we can't
try to connect to a different SSID while connected/ing; ensure
that prev_bssid is set for re-association attempts even in the
case of the driver supporting the connect() method, and don't
reset ssid_len in the failure cases.

While at it, also reset ssid_len while disconnecting unless we
were connected and expect a disconnected event, and warn on a
successful connection without ssid_len being set.

Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
net/wireless/sme.c | 50 +++++++++++++++++++++++++++++++++++++++++---------
1 file changed, 41 insertions(+), 9 deletions(-)

--- a/net/wireless/sme.c
+++ b/net/wireless/sme.c
@@ -505,11 +505,6 @@ static int cfg80211_sme_connect(struct w
return -EOPNOTSUPP;

if (wdev->current_bss) {
- if (!prev_bssid)
- return -EALREADY;
- if (prev_bssid &&
- !ether_addr_equal(prev_bssid, wdev->current_bss->pub.bssid))
- return -ENOTCONN;
cfg80211_unhold_bss(wdev->current_bss);
cfg80211_put_bss(wdev->wiphy, &wdev->current_bss->pub);
wdev->current_bss = NULL;
@@ -1025,11 +1020,35 @@ int cfg80211_connect(struct cfg80211_reg

ASSERT_WDEV_LOCK(wdev);

- if (WARN_ON(wdev->connect_keys)) {
- kzfree(wdev->connect_keys);
- wdev->connect_keys = NULL;
+ /*
+ * If we have an ssid_len, we're trying to connect or are
+ * already connected, so reject a new SSID unless it's the
+ * same (which is the case for re-association.)
+ */
+ if (wdev->ssid_len &&
+ (wdev->ssid_len != connect->ssid_len ||
+ memcmp(wdev->ssid, connect->ssid, wdev->ssid_len)))
+ return -EALREADY;
+
+ /*
+ * If connected, reject (re-)association unless prev_bssid
+ * matches the current BSSID.
+ */
+ if (wdev->current_bss) {
+ if (!prev_bssid)
+ return -EALREADY;
+ if (!ether_addr_equal(prev_bssid, wdev->current_bss->pub.bssid))
+ return -ENOTCONN;
}

+ /*
+ * Reject if we're in the process of connecting with WEP,
+ * this case isn't very interesting and trying to handle
+ * it would make the code much more complex.
+ */
+ if (wdev->connect_keys)
+ return -EINPROGRESS;
+
cfg80211_oper_and_ht_capa(&connect->ht_capa_mask,
rdev->wiphy.ht_capa_mod_mask);

@@ -1080,7 +1099,12 @@ int cfg80211_connect(struct cfg80211_reg

if (err) {
wdev->connect_keys = NULL;
- wdev->ssid_len = 0;
+ /*
+ * This could be reassoc getting refused, don't clear
+ * ssid_len in that case.
+ */
+ if (!wdev->current_bss)
+ wdev->ssid_len = 0;
return err;
}

@@ -1105,5 +1129,13 @@ int cfg80211_disconnect(struct cfg80211_
else if (wdev->current_bss)
err = rdev_disconnect(rdev, dev, reason);

+ /*
+ * Clear ssid_len unless we actually were fully connected,
+ * in which case cfg80211_disconnected() will take care of
+ * this later.
+ */
+ if (!wdev->current_bss)
+ wdev->ssid_len = 0;
+
return err;
}