4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jason Wang <jasowang@xxxxxxxxxx> [ Upstream commit addf8fc4acb1cf79492ac64966f07178793cb3d7 ] We used to check dev->reg_state against NETREG_REGISTERED after each time we are woke up. But after commit 9e641bdcfa4e ("net-tun: restructure tun_do_read for better sleep/wakeup efficiency"), it uses skb_recv_datagram() which does not check dev->reg_state. This will result if we delete a tun/tap device after a process is blocked in the reading. The device will wait for the reference count which was held by that process for ever. Fixes this by using RCV_SHUTDOWN which will be checked during sk_recv_datagram() before trying to wake up the process during uninit. Fixes: 9e641bdcfa4e ("net-tun: restructure tun_do_read for better sleep/wakeup efficiency") Cc: Eric Dumazet <edumazet@xxxxxxxxxx> Cc: Xi Wang <xii@xxxxxxxxxx> Cc: Michael S. Tsirkin <mst@xxxxxxxxxx> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx> Acked-by: Eric Dumazet <edumazet@xxxxxxxxxx> Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/net/tun.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -567,11 +567,13 @@ static void tun_detach_all(struct net_de for (i = 0; i < n; i++) { tfile = rtnl_dereference(tun->tfiles[i]); BUG_ON(!tfile); + tfile->socket.sk->sk_shutdown = RCV_SHUTDOWN; tfile->socket.sk->sk_data_ready(tfile->socket.sk); RCU_INIT_POINTER(tfile->tun, NULL); --tun->numqueues; } list_for_each_entry(tfile, &tun->disabled, next) { + tfile->socket.sk->sk_shutdown = RCV_SHUTDOWN; tfile->socket.sk->sk_data_ready(tfile->socket.sk); RCU_INIT_POINTER(tfile->tun, NULL); } @@ -627,6 +629,7 @@ static int tun_attach(struct tun_struct goto out; } tfile->queue_index = tun->numqueues; + tfile->socket.sk->sk_shutdown &= ~RCV_SHUTDOWN; rcu_assign_pointer(tfile->tun, tun); rcu_assign_pointer(tun->tfiles[tun->numqueues], tfile); tun->numqueues++; @@ -1408,9 +1411,6 @@ static ssize_t tun_do_read(struct tun_st if (!iov_iter_count(to)) return 0; - if (tun->dev->reg_state != NETREG_REGISTERED) - return -EIO; - /* Read frames from queue */ skb = __skb_recv_datagram(tfile->socket.sk, noblock ? MSG_DONTWAIT : 0, &peeked, &off, &err); -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html