Siddh Raman Pant [off-list ref] writes:

ieee80211_scan_rx() tries to access scan_req->flags after a null check
(see line 303 of mac80211/scan.c), but ___cfg80211_scan_done() uses
kfree() on the scan_req (see line 991 of wireless/scan.c).

This results in a UAF.

ieee80211_scan_rx() is called inside a RCU read-critical section
initiated by ieee80211_rx_napi() (see line 5043 of mac80211/rx.c).

Thus, add an rcu_head to the scan_req struct so as to use kfree_rcu()
instead of kfree() so that we don't free during the critical section.

Bug report (3): https://syzkaller.appspot.com/bug?extid=f9acff9bf08a845f225d
Reported-by: syzbot+f9acff9bf08a845f225d@syzkaller.appspotmail.com
Reported-by: syzbot+6cb476b7c69916a0caca@syzkaller.appspotmail.com
Reported-by: syzbot+9250865a55539d384347@syzkaller.appspotmail.com

Signed-off-by: Siddh Raman Pant <redacted>
---
 include/net/cfg80211.h | 2 ++
 net/wireless/scan.c    | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

The title should be:

wifi: cfg80211: Fix UAF in ieee80211_scan_rx()

-- 
https://patchwork.kernel.org/project/linux-wireless/list/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches