This is a note to let you know that I've just added the patch titled mac80211: remove warning in ieee80211_get_sband() to the 4.19-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: mac80211-remove-warning-in-ieee80211_get_sband.patch and it can be found in the queue-4.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 03feffb6d582056892897bd534e9646623870fc2 Author: Johannes Berg <johannes.berg@xxxxxxxxx> Date: Mon May 17 16:47:17 2021 +0200 mac80211: remove warning in ieee80211_get_sband() [ Upstream commit 0ee4d55534f82a0624701d0bb9fc2304d4529086 ] Syzbot reports that it's possible to hit this from userspace, by trying to add a station before any other connection setup has been done. Instead of trying to catch this in some other way simply remove the warning, that will appropriately reject the call from userspace. Reported-by: syzbot+7716dbc401d9a437890d@xxxxxxxxxxxxxxxxxxxxxxxxx Link: https://lore.kernel.org/r/20210517164715.f537da276d17.Id05f40ec8761d6a8cc2df87f1aa09c651988a586@changeid Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h index 6c9d9c94983b..dea48696f994 100644 --- a/net/mac80211/ieee80211_i.h +++ b/net/mac80211/ieee80211_i.h @@ -1398,7 +1398,7 @@ ieee80211_get_sband(struct ieee80211_sub_if_data *sdata) rcu_read_lock(); chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf); - if (WARN_ON_ONCE(!chanctx_conf)) { + if (!chanctx_conf) { rcu_read_unlock(); return NULL; }