Commit 9ad48cbf authored Aug 20, 2022 by Siddh Raman Pant Committed by Greg Kroah-Hartman Sep 28, 2022

wifi: mac80211: Fix UAF in ieee80211_scan_rx()

[ Upstream commit 60deb9f10eec5c6a20252ed36238b55d8b614a2c ]

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: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Siddh Raman Pant <code@siddh.me>
Link: https://lore.kernel.org/r/20220819200340.34826-1-code@siddh.me


Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 9a3695bd

net/mac80211/scan.c

+7 −4

Original line number	Diff line number	Diff line
		@@ -431,10 +431,6 @@ 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);

		scan_sdata = rcu_dereference_protected(local->scan_sdata,
		@@ -444,6 +440,13 @@ static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
		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);