From patchwork Fri Feb 9 15:00:18 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Chapman X-Patchwork-Id: 871437 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3zdJFW29F4z9s7f for ; Sat, 10 Feb 2018 02:02:23 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752524AbeBIPCW (ORCPT ); Fri, 9 Feb 2018 10:02:22 -0500 Received: from mail.katalix.com ([82.103.140.233]:38413 "EHLO mail.katalix.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751299AbeBIPAg (ORCPT ); Fri, 9 Feb 2018 10:00:36 -0500 Received: from katalix.com (82-69-108-24.dsl.in-addr.zen.co.uk [82.69.108.24]) (Authenticated sender: james) by mail.katalix.com (Postfix) with ESMTPSA id D0E227E2DF for ; Fri, 9 Feb 2018 15:00:34 +0000 (GMT) From: James Chapman To: netdev@vger.kernel.org Subject: [PATCH net-next 02/16] l2tp: add RCU read lock to protect tunnel ptr in ip socket destroy Date: Fri, 9 Feb 2018 15:00:18 +0000 Message-Id: <1518188432-9245-3-git-send-email-jchapman@katalix.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1518188432-9245-1-git-send-email-jchapman@katalix.com> References: <1518188432-9245-1-git-send-email-jchapman@katalix.com> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org If an L2TPIP socket is closed, add RCU protection when we deref sk_user_data to prevent races with another thread closing the same tunnel. Fixes: 0d76751fad ("l2tp: Add L2TPv3 IP encapsulation (no UDP) support") refcount_t: increment on 0; use-after-free. WARNING: CPU: 2 PID: 2892 at lib/refcount.c:153 refcount_inc+0x2b/0x30 Modules linked in: CPU: 2 PID: 2892 Comm: pppol2tp_chaos Not tainted 4.15.0-rc9+ #1 Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006 RIP: 0010:refcount_inc+0x2b/0x30 RSP: 0018:ffff880014147b50 EFLAGS: 00010282 RAX: 000000000000002b RBX: ffff8800194785c0 RCX: 0000000000000000 RDX: 0000000000000001 RSI: ffff88001ad1f758 RDI: ffff88001ad1f758 RBP: ffff880014147b50 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000001 R12: ffff8800194785c8 R13: ffff8800194785c0 R14: ffff88001a2c6c20 R15: ffff880013a9d580 FS: 0000000000000000(0000) GS:ffff88001ad00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fbc17ea7000 CR3: 0000000003022000 CR4: 00000000000006e0 Call Trace: l2tp_tunnel_delete+0x34/0x60 l2tp_ip_destroy_sock+0x6d/0x80 sk_common_release+0x19/0xd0 l2tp_ip_close+0x89/0xa0 inet_release+0x37/0x60 sock_release+0x1a/0x70 sock_close+0xd/0x20 __fput+0xed/0x1f0 ____fput+0x9/0x10 task_work_run+0x77/0xb0 do_exit+0x311/0xcf0 do_group_exit+0x47/0xc0 get_signal+0x343/0x8e0 do_signal+0x23/0x780 ? find_held_lock+0x39/0xb0 exit_to_usermode_loop+0x4a/0x93 syscall_return_slowpath+0x102/0x150 entry_SYSCALL_64_fastpath+0x98/0x9a RIP: 0033:0x7fbc172d7fcf RSP: 002b:00007ffd524cd4d8 EFLAGS: 00000246 ORIG_RAX: 000000000000000e RAX: 0000000000000000 RBX: 0000000000000006 RCX: 00007fbc172d7fcf RDX: 0000000000000000 RSI: 00007ffd524cd460 RDI: 0000000000000002 RBP: 0000000000404930 R08: 0000000000000000 R09: 00007ffd524cd460 R10: 0000000000000008 R11: 0000000000000246 R12: 000000000000001e R13: 0000000000404a03 R14: 0000000000000000 R15: 0000000000000000 Code: 55 48 89 e5 e8 87 ff ff ff 84 c0 74 02 5d c3 80 3d 97 87 bb 01 00 75 f5 48 c7 c7 58 3e cc 82 c6 05 87 87 bb 01 Signed-off-by: James Chapman --- net/l2tp/l2tp_ip.c | 5 ++++- net/l2tp/l2tp_ip6.c | 5 ++++- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c index ff61124fdf59..42f3c2f72bf4 100644 --- a/net/l2tp/l2tp_ip.c +++ b/net/l2tp/l2tp_ip.c @@ -234,15 +234,18 @@ static void l2tp_ip_close(struct sock *sk, long timeout) static void l2tp_ip_destroy_sock(struct sock *sk) { struct sk_buff *skb; - struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk); + struct l2tp_tunnel *tunnel; while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL) kfree_skb(skb); + rcu_read_lock(); + tunnel = rcu_dereference_sk_user_data(sk); if (tunnel) { l2tp_tunnel_closeall(tunnel); sock_put(sk); } + rcu_read_unlock(); sk_refcnt_debug_dec(sk); } diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c index 192344688c06..be4a3eee85a9 100644 --- a/net/l2tp/l2tp_ip6.c +++ b/net/l2tp/l2tp_ip6.c @@ -248,16 +248,19 @@ static void l2tp_ip6_close(struct sock *sk, long timeout) static void l2tp_ip6_destroy_sock(struct sock *sk) { - struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk); + struct l2tp_tunnel *tunnel; lock_sock(sk); ip6_flush_pending_frames(sk); release_sock(sk); + rcu_read_lock(); + tunnel = rcu_dereference_sk_user_data(sk); if (tunnel) { l2tp_tunnel_closeall(tunnel); sock_put(sk); } + rcu_read_unlock(); inet6_destroy_sock(sk); }