From: Johannes Berg johannes.berg@intel.com
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 keescook@chromium.org Signed-off-by: Johannes Berg johannes.berg@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/mac80211/util.c | 2 ++ net/wireless/scan.c | 2 ++ 2 files changed, 4 insertions(+)
--- a/net/mac80211/util.c +++ b/net/mac80211/util.c @@ -1442,6 +1442,8 @@ static size_t ieee802_11_find_bssid_prof 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]; --- a/net/wireless/scan.c +++ b/net/wireless/scan.c @@ -2143,6 +2143,8 @@ static void cfg80211_parse_mbssid_data(s 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;