package/kernel/mac80211/patches/subsys/340-v5.19-wifi-mac80211-do-not-abuse-fq.lock-in-ieee80211_do_s.patch

   1 From aa40d5a43526cca9439a2b45fcfdcd016594dece Mon Sep 17 00:00:00 2001
   2 From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
   3 Date: Sun, 17 Jul 2022 21:21:52 +0900
   4 Subject: [PATCH] wifi: mac80211: do not abuse fq.lock in ieee80211_do_stop()
   5 MIME-Version: 1.0
   6 Content-Type: text/plain; charset=UTF-8
   7 Content-Transfer-Encoding: 8bit
   8
   9 lockdep complains use of uninitialized spinlock at ieee80211_do_stop() [1],
  10 for commit f856373e2f31ffd3 ("wifi: mac80211: do not wake queues on a vif
  11 that is being stopped") guards clear_bit() using fq.lock even before
  12 fq_init() from ieee80211_txq_setup_flows() initializes this spinlock.
  13
  14 According to discussion [2], Toke was not happy with expanding usage of
  15 fq.lock. Since __ieee80211_wake_txqs() is called under RCU read lock, we
  16 can instead use synchronize_rcu() for flushing ieee80211_wake_txqs().
  17
  18 Link: https://syzkaller.appspot.com/bug?extid=eceab52db7c4b961e9d6 [1]
  19 Link: https://lkml.kernel.org/r/874k0zowh2.fsf@toke.dk [2]
  20 Reported-by: syzbot <syzbot+eceab52db7c4b961e9d6@syzkaller.appspotmail.com>
  21 Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
  22 Fixes: f856373e2f31ffd3 ("wifi: mac80211: do not wake queues on a vif that is being stopped")
  23 Tested-by: syzbot <syzbot+eceab52db7c4b961e9d6@syzkaller.appspotmail.com>
  24 Acked-by: Toke Høiland-Jørgensen <toke@kernel.org>
  25 Signed-off-by: Kalle Valo <kvalo@kernel.org>
  26 Link: https://lore.kernel.org/r/9cc9b81d-75a3-3925-b612-9d0ad3cab82b@I-love.SAKURA.ne.jp
  27 [ pick up commit 3598cb6e1862 ("wifi: mac80211: do not abuse fq.lock in ieee80211_do_stop()") from -next]
  28 Link: https://lore.kernel.org/all/87o7xcq6qt.fsf@kernel.org/
  29 Signed-off-by: Jakub Kicinski <kuba@kernel.org>
  30 ---
  31  net/mac80211/iface.c | 3 +--
  32  1 file changed, 1 insertion(+), 2 deletions(-)
  33
  34 --- a/net/mac80211/iface.c
  35 +++ b/net/mac80211/iface.c
  36 @@ -377,9 +377,8 @@ static void ieee80211_do_stop(struct iee
  37         bool cancel_scan;
  38         struct cfg80211_nan_func *func;
  39
  40 -       spin_lock_bh(&local->fq.lock);
  41         clear_bit(SDATA_STATE_RUNNING, &sdata->state);
  42 -       spin_unlock_bh(&local->fq.lock);
  43 +       synchronize_rcu(); /* flush _ieee80211_wake_txqs() */
  44
  45         cancel_scan = rcu_access_pointer(local->scan_sdata) == sdata;
  46         if (cancel_scan)