mac80211: pause TX while changing interface type

[ Upstream commit 054c9939b4800a91475d8d89905827bf9e1ad97a ]

syzbot reported a crash that happened when changing the interface
type around a lot, and while it might have been easy to fix just
the symptom there, a little deeper investigation found that really
the reason is that we allowed packets to be transmitted while in
the middle of changing the interface type.

Disallow TX by stopping the queues while changing the type.

Fixes: 34d4bc4d41d2 ("mac80211: support runtime interface type changes")
Reported-by: syzbot+d7a3b15976bf7de2238a@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/20210122171115.b321f98f4d4f.I6997841933c17b093535c31d29355be3c0c39628@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 0b0de3030e0dc1945da1fe28bb0d46509373645a..9c20c53f6729e15dc5fe69693117b235a400c1dd 100644 (file)
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1046,6 +1046,7 @@ enum queue_stop_reason {
        IEEE80211_QUEUE_STOP_REASON_FLUSH,
        IEEE80211_QUEUE_STOP_REASON_TDLS_TEARDOWN,
        IEEE80211_QUEUE_STOP_REASON_RESERVE_TID,
+       IEEE80211_QUEUE_STOP_REASON_IFTYPE_CHANGE,
 
        IEEE80211_QUEUE_STOP_REASONS,
 };

diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index ad03331ee78553897de33775e8f83e6711ac687d..7d43e0085cfc76641923154dc28b89897834c1a8 100644 (file)
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -1577,6 +1577,10 @@ static int ieee80211_runtime_change_iftype(struct ieee80211_sub_if_data *sdata,
        if (ret)
                return ret;
 
+       ieee80211_stop_vif_queues(local, sdata,
+                                 IEEE80211_QUEUE_STOP_REASON_IFTYPE_CHANGE);
+       synchronize_net();
+
        ieee80211_do_stop(sdata, false);
 
        ieee80211_teardown_sdata(sdata);
@@ -1597,6 +1601,8 @@ static int ieee80211_runtime_change_iftype(struct ieee80211_sub_if_data *sdata,
        err = ieee80211_do_open(&sdata->wdev, false);
        WARN(err, "type change: do_open returned %d", err);
 
+       ieee80211_wake_vif_queues(local, sdata,
+                                 IEEE80211_QUEUE_STOP_REASON_IFTYPE_CHANGE);
        return ret;
 }