From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932345AbeAaAoC (ORCPT ); Tue, 30 Jan 2018 19:44:02 -0500 Received: from mail-io0-f193.google.com ([209.85.223.193]:38630 "EHLO mail-io0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932125AbeAaAoA (ORCPT ); Tue, 30 Jan 2018 19:44:00 -0500 X-Google-Smtp-Source: AH8x225BnFI4VR41Bj4EB8xO3GwNyv0JE8rUGTPBm4LL32uWDzw7ST5dHpYBkJ7zy5FCafDvsrai6A== Date: Tue, 30 Jan 2018 16:43:57 -0800 From: Eric Biggers To: syzbot Cc: davem@davemloft.net, kuznet@ms2.inr.ac.ru, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com, yoshfuji@linux-ipv6.org Subject: Re: suspicious RCU usage at ./include/linux/inetdevice.h:LINE Message-ID: <20180131004357.qpbxrfkgev4kljpg@gmail.com> References: <001a114a958cf58255055cfdccb2@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <001a114a958cf58255055cfdccb2@google.com> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 02, 2017 at 03:53:38AM -0700, syzbot wrote: > Hello, > > syzkaller hit the following crash on > ce43f4fd6f103681c7485c2b1967179647e73555 > git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/master > compiler: gcc (GCC) 7.1.1 20170620 > .config is attached > Raw console output is attached. > > > > > > ============================= > WARNING: suspicious RCU usage > 4.14.0-rc5+ #140 Not tainted > ----------------------------- > ./include/linux/inetdevice.h:230 suspicious rcu_dereference_protected() > usage! > > other info that might help us debug this: > > > rcu_scheduler_active = 2, debug_locks = 1 > 1 lock held by syz-executor2/23859: > #0: (rcu_read_lock){....}, at: [] > inet_rtm_getroute+0xaa0/0x2d70 net/ipv4/route.c:2738 > > stack backtrace: > CPU: 0 PID: 23859 Comm: syz-executor2 Not tainted 4.14.0-rc5+ #140 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:16 [inline] > dump_stack+0x194/0x257 lib/dump_stack.c:52 > lockdep_rcu_suspicious+0x123/0x170 kernel/locking/lockdep.c:4665 > __in_dev_get_rtnl include/linux/inetdevice.h:230 [inline] > fib_dump_info+0x1136/0x13d0 net/ipv4/fib_semantics.c:1377 > inet_rtm_getroute+0xf97/0x2d70 net/ipv4/route.c:2785 > rtnetlink_rcv_msg+0x51c/0x1090 net/core/rtnetlink.c:4237 > netlink_rcv_skb+0x216/0x440 net/netlink/af_netlink.c:2409 > rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:4261 > netlink_unicast_kernel net/netlink/af_netlink.c:1273 [inline] > netlink_unicast+0x4e8/0x6f0 net/netlink/af_netlink.c:1299 > netlink_sendmsg+0xa4a/0xe60 net/netlink/af_netlink.c:1862 > sock_sendmsg_nosec net/socket.c:633 [inline] > sock_sendmsg+0xca/0x110 net/socket.c:643 > sock_write_iter+0x31a/0x5d0 net/socket.c:912 > call_write_iter include/linux/fs.h:1770 [inline] > new_sync_write fs/read_write.c:468 [inline] > __vfs_write+0x684/0x970 fs/read_write.c:481 > vfs_write+0x189/0x510 fs/read_write.c:543 > SYSC_write fs/read_write.c:588 [inline] > SyS_write+0xef/0x220 fs/read_write.c:580 > entry_SYSCALL_64_fastpath+0x1f/0xbe > RIP: 0033:0x452719 > RSP: 002b:00007fd087b03be8 EFLAGS: 00000212 ORIG_RAX: 0000000000000001 > RAX: ffffffffffffffda RBX: 0000000000758020 RCX: 0000000000452719 > RDX: 0000000000000024 RSI: 0000000020226000 RDI: 0000000000000014 > RBP: 0000000000000082 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000212 R12: 0000000000000000 > R13: 0000000000a6f7ff R14: 00007fd087b049c0 R15: 0000000000000000 No longer seeing this crash. I assume it was fixed by the following commit (thanks Florian!), so telling syzbot: #syz fix: fib: fib_dump_info can no longer use __in_dev_get_rtnl