From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753612AbcFIVUy (ORCPT ); Thu, 9 Jun 2016 17:20:54 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:51675 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161181AbcFIVUu (ORCPT ); Thu, 9 Jun 2016 17:20:50 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Eric Dumazet , Xi Wang , "Michael S . Tsirkin" , Jason Wang , "David S . Miller" , Kamal Mostafa Subject: [PATCH 4.2.y-ckt 203/206] tuntap: correctly wake up process during uninit Date: Thu, 9 Jun 2016 14:16:52 -0700 Message-Id: <1465507015-23052-204-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1465507015-23052-1-git-send-email-kamal@canonical.com> References: <1465507015-23052-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 4.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.2.8-ckt12 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ From: Jason Wang commit addf8fc4acb1cf79492ac64966f07178793cb3d7 upstream. 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: Kamal Mostafa --- drivers/net/tun.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 6049086..2405f4e 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -567,11 +567,13 @@ static void tun_detach_all(struct net_device *dev) 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 *tun, struct file *file, bool skip_filte 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++; @@ -1409,9 +1412,6 @@ static ssize_t tun_do_read(struct tun_struct *tun, struct tun_file *tfile, 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); -- 2.7.4