diff mbox series

[SRU,OEM-6.0,2/9] wifi: cfg80211/mac80211: reject bad MBSSID elements

Message ID 20221018174312.3383944-3-cascardo@canonical.com
State New
Headers show
Series wlan CVE fixes | expand

Commit Message

Thadeu Lima de Souza Cascardo Oct. 18, 2022, 5:43 p.m. UTC 
From: Johannes Berg <johannes.berg@intel.com>

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 <keescook@chromium.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
(cherry picked from commit 8f033d2becc24aa6bfd2a5c104407963560caabc)
CVE-2022-41674
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
---
 net/mac80211/util.c | 2 ++
 net/wireless/scan.c | 2 ++
 2 files changed, 4 insertions(+)
diff mbox series

Patch

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;