From: Johannes Berg <[email protected]> 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. Cc: [email protected] Fixes: 0b8fb8235be8 ("cfg80211: Parsing of Multiple BSSID information in scanning") Link: https://lore.kernel.org/r/1569009255-I1673911f5eae02964e21bdc11b2bf58e5e207e59@changeid Signed-off-by: Johannes Berg <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- net/wireless/scan.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/net/wireless/scan.c +++ b/net/wireless/scan.c @@ -1711,7 +1711,12 @@ cfg80211_update_notlisted_nontrans(struc return; 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) return; new_ie_len -= mbssid[1]; rcu_read_lock();
