wifi: cfg80211: wext: set ssids=NULL for passive scans

commit 0941772342d59e48733131ac3a202fa1a4d832e9 upstream.

In nl80211, we always set the ssids of a scan request to
NULL when n_ssids==0 (passive scan). Drivers have relied
on this behaviour in the past, so we fixed it in 6 GHz
scan requests as well, and added a warning so we'd have
assurance the API would always be called that way.

syzbot found that wext doesn't ensure that, so we reach
the check and trigger the warning. Fix the wext code to
set the ssids pointer to NULL when there are none.

Reported-by: syzbot+cd6135193ba6bb9ad158@syzkaller.appspotmail.com
Fixes: f7a8b10bfd61 ("wifi: cfg80211: fix 6 GHz scan request building")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index a811ad02e6d1ff40031e06919f8653b94e82586b..fba5e98bf493a0e03b243d54bd705206bcc62585 100644 (file)
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -3492,8 +3492,10 @@ int cfg80211_wext_siwscan(struct net_device *dev,
                        memcpy(creq->ssids[0].ssid, wreq->essid, wreq->essid_len);
                        creq->ssids[0].ssid_len = wreq->essid_len;
                }
-               if (wreq->scan_type == IW_SCAN_TYPE_PASSIVE)
+               if (wreq->scan_type == IW_SCAN_TYPE_PASSIVE) {
+                       creq->ssids = NULL;
                        creq->n_ssids = 0;
+               }
        }
 
        for (i = 0; i < NUM_NL80211_BANDS; i++)