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tuntap: fix possible deadlock when fail to register netdev

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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: 96f8406162 ("tun: add eBPF based queue selection method")
Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jason Wang 2017-12-08 12:02:30 +08:00 committed by David S. Miller
parent 66c5c5b566
commit 124da8f611
1 changed files with 4 additions and 3 deletions
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7
drivers/net/tun.c
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@ -2048,8 +2048,11 @@ static int __tun_set_steering_ebpf(struct tun_struct *tun,
new->prog = prog; 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); rcu_assign_pointer(tun->steering_prog, new);
spin_unlock_bh(&tun->lock);
if (old) if (old)
call_rcu(&old->rcu, tun_steering_prog_free); 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); free_percpu(tun->pcpu_stats);
tun_flow_uninit(tun); tun_flow_uninit(tun);
security_tun_dev_free_security(tun->security); security_tun_dev_free_security(tun->security);
rtnl_lock();
__tun_set_steering_ebpf(tun, NULL); __tun_set_steering_ebpf(tun, NULL);
rtnl_unlock();
} }
static void tun_setup(struct net_device *dev) static void tun_setup(struct net_device *dev)