mac80211: disable powersave for broken APs

commit 05cb91085760ca378f28fc274fbf77fc4fd9886c upstream.

Only AID values 1-2007 are valid, but some APs have been
found to send random bogus values, in the reported case an
AP that was sending the AID field value 0xffff, an AID of
0x3fff (16383).

There isn't much we can do but disable powersave since
there's no way it can work properly in this case.

Reported-by: Bill C Riemers <briemers@redhat.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 7a334fd..1563250 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -613,6 +613,9 @@
 	if (!mgd->powersave)
 		return false;
 
+	if (mgd->broken_ap)
+		return false;
+
 	if (!mgd->associated)
 		return false;
 
@@ -1450,10 +1453,21 @@
 	capab_info = le16_to_cpu(mgmt->u.assoc_resp.capab_info);
 
 	if ((aid & (BIT(15) | BIT(14))) != (BIT(15) | BIT(14)))
-		printk(KERN_DEBUG "%s: invalid aid value %d; bits 15:14 not "
-		       "set\n", sdata->name, aid);
+		printk(KERN_DEBUG
+		       "%s: invalid AID value 0x%x; bits 15:14 not set\n",
+		       sdata->name, aid);
 	aid &= ~(BIT(15) | BIT(14));
 
+	ifmgd->broken_ap = false;
+
+	if (aid == 0 || aid > IEEE80211_MAX_AID) {
+		printk(KERN_DEBUG
+		       "%s: invalid AID value %d (out of range), turn off PS\n",
+		       sdata->name, aid);
+		aid = 0;
+		ifmgd->broken_ap = true;
+	}
+
 	pos = mgmt->u.assoc_resp.variable;
 	ieee802_11_parse_elems(pos, len - (pos - (u8 *) mgmt), &elems);