wifi: cfg80211: don't allow multi-BSSID in S1G

In S1G beacon frames there shouldn't be multi-BSSID elements
since that's not supported, remove that to avoid a potential
integer underflow and/or misparsing the frames due to the
different length of the fixed part of the frame.

While at it, initialize non_tx_data so we don't send garbage
values to the user (even if it doesn't seem to matter now.)

Reported-and-tested-by: Sönke Huster <shuster@seemoo.tu-darmstadt.de>
Fixes: 9eaffe5078ca ("cfg80211: convert S1G beacon to scan results")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index 4d21779..3d86482 100644 (file)
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -2527,10 +2527,15 @@ cfg80211_inform_bss_frame_data(struct wiphy *wiphy,
        const struct cfg80211_bss_ies *ies1, *ies2;
        size_t ielen = len - offsetof(struct ieee80211_mgmt,
                                      u.probe_resp.variable);
-       struct cfg80211_non_tx_bss non_tx_data;
+       struct cfg80211_non_tx_bss non_tx_data = {};
 
        res = cfg80211_inform_single_bss_frame_data(wiphy, data, mgmt,
                                                    len, gfp);
+
+       /* don't do any further MBSSID handling for S1G */
+       if (ieee80211_is_s1g_beacon(mgmt->frame_control))
+               return res;
+
        if (!res || !wiphy->support_mbssid ||
            !cfg80211_find_elem(WLAN_EID_MULTIPLE_BSSID, ie, ielen))
                return res;