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 a879d8071712bfec0bcba37e18ed9795e2015cff..fc715bba59146f2ddfe84987d5582f781a205b16 100644 (file)
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1051,6 +1051,7 @@ 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 152d4365f9616bccb9bbf46f2ff318a3990d72b6..511ca6f74239d39a0df718bf732fa321dd9241d9 100644 (file)
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -1542,6 +1542,10 @@ 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);
@@ -1562,6 +1566,8 @@ 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;
 }