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Commit 124da8f6 authored by Jason Wang's avatar Jason Wang Committed by David S. Miller
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tuntap: fix possible deadlock when fail to register netdev 



Private destructor could be called when register_netdev() fail with
rtnl lock held. This will lead deadlock in tun_free_netdev() who tries
to hold rtnl_lock. Fixing this by switching to use spinlock to
synchronize.

Fixes: 96f84061 ("tun: add eBPF based queue selection method")
Reported-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
Acked-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 66c5c5b5

drivers/net/tun.c

+4 −3
Original line number Diff line number Diff line
@@ -2048,8 +2048,11 @@ static int __tun_set_steering_ebpf(struct tun_struct *tun, 
		new->prog = prog;

	}



	old = rtnl_dereference(tun->steering_prog);

	spin_lock_bh(&tun->lock);

	old = rcu_dereference_protected(tun->steering_prog,

					lockdep_is_held(&tun->lock));

	rcu_assign_pointer(tun->steering_prog, new);

	spin_unlock_bh(&tun->lock);



	if (old)

		call_rcu(&old->rcu, tun_steering_prog_free);
@@ -2065,9 +2068,7 @@ static void tun_free_netdev(struct net_device *dev) 
	free_percpu(tun->pcpu_stats);

	tun_flow_uninit(tun);

	security_tun_dev_free_security(tun->security);

	rtnl_lock();

	__tun_set_steering_ebpf(tun, NULL);

	rtnl_unlock();

}



static void tun_setup(struct net_device *dev)