wifi: mac80211: Fix UAF in ieee80211_scan_rx()

stable inclusion
from stable-v5.10.142
commit 4abc8c07a065ecf771827bde3c63fbbe4aa0c08b
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6CSFH

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4abc8c07a065ecf771827bde3c63fbbe4aa0c08b

--------------------------------

commit 60deb9f1 upstream.

ieee80211_scan_rx() tries to access scan_req->flags after a
null check, but a UAF is observed when the scan is completed
and __ieee80211_scan_completed() executes, which then calls
cfg80211_scan_done() leading to the freeing of scan_req.

Since scan_req is rcu_dereference()'d, prevent the racing in
__ieee80211_scan_completed() by ensuring that from mac80211's
POV it is no longer accessed from an RCU read critical section
before we call cfg80211_scan_done().

Cc: stable@vger.kernel.org
Link: https://syzkaller.appspot.com/bug?extid=f9acff9bf08a845f225d
Reported-by: syzbot+f9acff9bf08a845f225d@syzkaller.appspotmail.com
Suggested-by: NJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: NSiddh Raman Pant <code@siddh.me>
Link: https://lore.kernel.org/r/20220819200340.34826-1-code@siddh.meSigned-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NJialin Zhang <zhangjialin11@huawei.com>
Reviewed-by: NZheng Zengkai <zhengzengkai@huawei.com>

net/mac80211/scan.c

@@ -463,16 +463,19 @@ static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 	scan_req = rcu_dereference_protected(local->scan_req,
 					     lockdep_is_held(&local->mtx));
 
-	if (scan_req != local->int_scan_req) {
-		local->scan_info.aborted = aborted;
-		cfg80211_scan_done(scan_req, &local->scan_info);
-	}
 	RCU_INIT_POINTER(local->scan_req, NULL);
 	RCU_INIT_POINTER(local->scan_sdata, NULL);
 
 	local->scanning = 0;
 	local->scan_chandef.chan = NULL;
 
+	synchronize_rcu();
+
+	if (scan_req != local->int_scan_req) {
+		local->scan_info.aborted = aborted;
+		cfg80211_scan_done(scan_req, &local->scan_info);
+	}
+
 	/* Set power back to normal operating levels. */
 	ieee80211_hw_config(local, 0);