blob: aef46b86ab2a982bf72c7183f72fec65bc2adaff [file] [log] [blame]
From a8eaf0dd2d0cdff698418155b50218925e63e405 Mon Sep 17 00:00:00 2001
From: Johannes Berg <>
Date: Fri, 20 Sep 2019 21:54:18 +0200
Subject: [PATCH] cfg80211: validate SSID/MBSSID element ordering assumption
commit 242b0931c1918c56cd1dc5563fd250a3c39b996d upstream.
The code copying the data assumes that the SSID element is
before the MBSSID element, but since the data is untrusted
from the AP, this cannot be guaranteed.
Validate that this is indeed the case and ignore the MBSSID
otherwise, to avoid having to deal with both cases for the
copy of data that should be between them.
Fixes: 0b8fb8235be8 ("cfg80211: Parsing of Multiple BSSID information in scanning")
Signed-off-by: Johannes Berg <>
Signed-off-by: Paul Gortmaker <>
diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index aa571d727903..43f81ba4c290 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -1710,7 +1710,12 @@ cfg80211_update_notlisted_nontrans(struct wiphy *wiphy,
new_ie_len -= trans_ssid[1];
mbssid = cfg80211_find_ie(WLAN_EID_MULTIPLE_BSSID, ie, ielen);
- if (!mbssid)
+ /*
+ * It's not valid to have the MBSSID element before SSID
+ * ignore if that happens - the code below assumes it is
+ * after (while copying things inbetween).
+ */
+ if (!mbssid || mbssid < trans_ssid)
new_ie_len -= mbssid[1];