From patchwork Thu Feb 11 21:13:38 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sven Eckelmann X-Patchwork-Id: 5047 Return-Path: Received-SPF: Pass (sender SPF authorized) identity=mailfrom; client-ip=79.140.41.39; helo=v3-1039.vlinux.de; envelope-from=sven@narfation.org; receiver=b.a.t.m.a.n@lists.open-mesh.org Authentication-Results: open-mesh.org; dmarc=pass header.from=narfation.org Authentication-Results: open-mesh.org; dkim=pass reason="1024-bit key; unprotected key" header.d=narfation.org header.i=@narfation.org header.b=fp4ef7xI; dkim-adsp=pass; dkim-atps=neutral Received: from v3-1039.vlinux.de (narfation.org [79.140.41.39]) by open-mesh.org (Postfix) with ESMTPS id 1E2638157E for ; Thu, 11 Feb 2016 22:13:46 +0100 (CET) Received: from sven-desktop.home.narfation.org (p200300C593C061FD0000000000002E16.dip0.t-ipconnect.de [IPv6:2003:c5:93c0:61fd::2e16]) by v3-1039.vlinux.de (Postfix) with ESMTPSA id A04681C8001; Thu, 11 Feb 2016 22:13:45 +0100 (CET) Authentication-Results: v3-1039.vlinux.de; dmarc=none header.from=narfation.org DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=narfation.org; s=20121; t=1455225225; bh=9nA25aP2+f2U1xnmjhtc9/5jbPHchiiI67UG/dPR4yc=; h=From:To:Cc:Subject:Date:From; b=fp4ef7xI9KZKg8A7kScrnBdiqckv7irMFDaPkg7W8JgOMEXBtCkMxBE3F3ZvmdU4x wZq3/cTafcc0eVBSgp0Eu1Ml4dKTSxYfgTRJ5MU9fW6c3NXVHhe5kExmsxlEssQNmD mgUzlE/KB2AXjOzbDhOztiJwexViu9Ov4QKvQzg4= From: Sven Eckelmann To: b.a.t.m.a.n@lists.open-mesh.org Date: Thu, 11 Feb 2016 22:13:38 +0100 Message-Id: <1455225218-13662-1-git-send-email-sven@narfation.org> X-Mailer: git-send-email 2.7.0 Subject: [B.A.T.M.A.N.] [PATCH-maint] batman-adv: Avoid endless loop in bat-on-bat netdevice check X-BeenThere: b.a.t.m.a.n@lists.open-mesh.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: The list for a Better Approach To Mobile Ad-hoc Networking List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 11 Feb 2016 21:13:48 -0000 From: Andrew Lunn batman-adv checks in different situation if a new device is already on top of a different batman-adv device. This is done by getting the iflink of a device and all its parent. It assumes that this iflink is always a parent device in an acyclic graph. But this assumption is broken by devices like veth which are actually a pair of two devices linked to each other. The recursive check would therefore get veth0 when calling dev_get_iflink on veth1. And it gets veth0 when calling dev_get_iflink with veth1. Creating a veth pair and loading batman-adv freezes parts of the system ip link add veth0 type veth peer name veth1 modprobe batman-adv An RCU stall will be detected on the system which cannot be fixed. INFO: rcu_sched self-detected stall on CPU 1: (5264 ticks this GP) idle=3e9/140000000000001/0 softirq=144683/144686 fqs=5249 (t=5250 jiffies g=46 c=45 q=43) Task dump for CPU 1: insmod R running task 0 247 245 0x00000008 ffffffff8151f140 ffffffff8107888e ffff88000fd141c0 ffffffff8151f140 0000000000000000 ffffffff81552df0 ffffffff8107b420 0000000000000001 ffff88000e3fa700 ffffffff81540b00 ffffffff8107d667 0000000000000001 Call Trace: [] ? rcu_dump_cpu_stacks+0x7e/0xd0 [] ? rcu_check_callbacks+0x3f0/0x6b0 [] ? hrtimer_run_queues+0x47/0x180 [] ? update_process_times+0x2d/0x50 [] ? tick_handle_periodic+0x1b/0x60 [] ? smp_trace_apic_timer_interrupt+0x5e/0x90 [] ? apic_timer_interrupt+0x82/0x90 [] ? __dev_get_by_index+0x37/0x40 [] ? batadv_hard_if_event+0xee/0x3a0 [batman_adv] [] ? register_netdevice_notifier+0x81/0x1a0 [...] This can be avoided by checking if two devices are each others parent and stopping the check in this situation. Fixes: 3d48811b27f5 ("batman-adv: prevent using any virtual device created on batman-adv as hard-interface") Signed-off-by: Andrew Lunn [sven@narfation.org: rewritten description, extracted fix] Signed-off-by: Sven Eckelmann --- net/batman-adv/hard-interface.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c index aea4d06..fbd3c91 100644 --- a/net/batman-adv/hard-interface.c +++ b/net/batman-adv/hard-interface.c @@ -79,6 +79,28 @@ out: } /** + * batadv_mutual_parents - check if two devices are each others parent + * @dev1: 1st net_device + * @dev: 2nd net_device + * + * veth devices come in pairs and each is the parent of the other! + * + * Return: true if the devices are each others parent, otherwise false + */ +static bool batadv_mutual_parents(const struct net_device *dev1, + const struct net_device *dev2) +{ + int dev1_parent_iflink = dev_get_iflink(dev1); + int dev2_parent_iflink = dev_get_iflink(dev2); + + if (!dev1_parent_iflink || !dev2_parent_iflink) + return false; + + return (dev1_parent_iflink == dev2->ifindex) && + (dev2_parent_iflink == dev1->ifindex); +} + +/** * batadv_is_on_batman_iface - check if a device is a batman iface descendant * @net_dev: the device to check * @@ -111,6 +133,9 @@ static bool batadv_is_on_batman_iface(const struct net_device *net_dev) if (WARN(!parent_dev, "Cannot find parent device")) return false; + if (batadv_mutual_parents(net_dev, parent_dev)) + return false; + ret = batadv_is_on_batman_iface(parent_dev); return ret;