From 8493abdd8f425b7940001fe0324e63b207c90f56 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Wed, 28 Sep 2022 22:01:37 +0200 Subject: [PATCH 05/13] wifi: cfg80211/mac80211: reject bad MBSSID elements commit 8f033d2becc24aa6bfd2a5c104407963560caabc upstream. Per spec, the maximum value for the MaxBSSID ('n') indicator is 8, and the minimum is 1 since a multiple BSSID set with just one BSSID doesn't make sense (the # of BSSIDs is limited by 2^n). Limit this in the parsing in both cfg80211 and mac80211, rejecting any elements with an invalid value. This fixes potentially bad shifts in the processing of these inside the cfg80211_gen_new_bssid() function later. I found this during the investigation of CVE-2022-41674 fixed by the previous patch. Fixes: 0b8fb8235be8 ("cfg80211: Parsing of Multiple BSSID information in scanning") Fixes: 78ac51f81532 ("mac80211: support multi-bssid") Reviewed-by: Kees Cook Signed-off-by: Johannes Berg Signed-off-by: Greg Kroah-Hartman --- net/mac80211/util.c | 2 ++ net/wireless/scan.c | 2 ++ 2 files changed, 4 insertions(+) diff --git a/net/mac80211/util.c b/net/mac80211/util.c index efcefb2dd882..3d097386b2b9 100644 --- a/net/mac80211/util.c +++ b/net/mac80211/util.c @@ -1442,6 +1442,8 @@ static size_t ieee802_11_find_bssid_profile(const u8 *start, size_t len, for_each_element_id(elem, WLAN_EID_MULTIPLE_BSSID, start, len) { if (elem->datalen < 2) continue; + if (elem->data[0] < 1 || elem->data[0] > 8) + continue; for_each_element(sub, elem->data + 1, elem->datalen - 1) { u8 new_bssid[ETH_ALEN]; diff --git a/net/wireless/scan.c b/net/wireless/scan.c index f59bfc09ca60..bce44485374d 100644 --- a/net/wireless/scan.c +++ b/net/wireless/scan.c @@ -2143,6 +2143,8 @@ static void cfg80211_parse_mbssid_data(struct wiphy *wiphy, for_each_element_id(elem, WLAN_EID_MULTIPLE_BSSID, ie, ielen) { if (elem->datalen < 4) continue; + if (elem->data[0] < 1 || (int)elem->data[0] > 8) + continue; for_each_element(sub, elem->data + 1, elem->datalen - 1) { u8 profile_len; -- 2.38.0