From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:54157 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964828AbcFQPg1 (ORCPT ); Fri, 17 Jun 2016 11:36:27 -0400 Subject: Patch "tuntap: correctly wake up process during uninit" has been added to the 4.6-stable tree To: jasowang@redhat.com, davem@davemloft.net, edumazet@google.com, gregkh@linuxfoundation.org, mst@redhat.com, xii@google.com Cc: , From: Date: Fri, 17 Jun 2016 08:36:26 -0700 Message-ID: <1466177786187104@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled tuntap: correctly wake up process during uninit to the 4.6-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: tuntap-correctly-wake-up-process-during-uninit.patch and it can be found in the queue-4.6 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From foo@baz Fri Jun 17 08:34:39 PDT 2016 From: Jason Wang Date: Thu, 19 May 2016 13:36:51 +0800 Subject: tuntap: correctly wake up process during uninit From: Jason Wang [ 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 Cc: Xi Wang Cc: Michael S. Tsirkin Signed-off-by: Jason Wang Acked-by: Eric Dumazet Acked-by: Michael S. Tsirkin Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/tun.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -568,11 +568,13 @@ 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); } @@ -628,6 +630,7 @@ 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++; @@ -1425,9 +1428,6 @@ 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); Patches currently in stable-queue which might be from jasowang@redhat.com are queue-4.6/tuntap-correctly-wake-up-process-during-uninit.patch