mac80211: fix locking in ieee80211_start_ap error path

commit 87a270625a89fc841f1a7e21aae6176543d8385c upstream.

We need to hold the local->mtx to release the channel context,
as even encoded by the lockdep_assert_held() there. Fix it.

Cc: stable@vger.kernel.org
Fixes: 295b02c4be74 ("mac80211: Add FILS discovery support")
Reported-and-tested-by: syzbot+11c342e5e30e9539cabd@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/20211220090836.cee3d59a1915.I36bba9b79dc2ff4d57c3c7aa30dff9a003fe8c5c@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index d3f62fd12f0b5a3e50a6b290cb1b33e6c053925a..1bf83b8d84021a1aae80e86f8d08b64a4c7baa08 100644 (file)
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -1226,7 +1226,10 @@ static int ieee80211_start_ap(struct wiphy *wiphy, struct net_device *dev,
        return 0;
 
 error:
+       mutex_lock(&local->mtx);
        ieee80211_vif_release_channel(sdata);
+       mutex_unlock(&local->mtx);
+
        return err;
 }