Return-Path: Received: from smtp.gentoo.org ([140.211.166.183]:40464 "EHLO smtp.gentoo.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752470AbdKMWsl (ORCPT ); Mon, 13 Nov 2017 17:48:41 -0500 Subject: Re: [nfsd4] potentially hardware breaking regression in 4.14-rc and 4.13.11 To: Linus Torvalds , Kees Cook Cc: Emese Revfy , Al Viro , Bruce Fields , "Darrick J. Wong" , Linux Kernel Mailing List , Linux NFS Mailing List , stable , Thorsten Leemhuis , "kernel-hardening@lists.openwall.com" References: <20171109193715.GB21978@ZenIV.linux.org.uk> <40ad7c6e-f0d7-959a-bf29-d3e3843f5d31@gentoo.org> <23f7da04-95f7-24e7-ee70-ce40c5b8fee3@gentoo.org> <67939ef3-29c6-762c-7afe-46cc69630d95@gentoo.org> From: Patrick McLean Message-ID: <3d948180-6bd7-c4e9-5ac8-5baef9cc15a7@gentoo.org> Date: Mon, 13 Nov 2017 14:48:38 -0800 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Sender: linux-nfs-owner@vger.kernel.org List-ID: On 2017-11-11 09:31 AM, Linus Torvalds wrote: > Boris Lukashev points out that Patrick should probably check a newer > version of gcc. > > I looked around, and in one of the emails, Patrick said: > > "No changes, both the working and broken kernels were built with > distro-provided gcc 5.4.0 and binutils 2.28.1" > > and gcc-5.4.0 is certainly not very recent. It's not _ancient_, but > it's a bug-fix release to a pretty old branch that is not exactly new. > > It would probably be good to check if the problems persist with gcc > 6.x or 7.x.. I have no idea which gcc version the randstruct people > tend to use themselves. I just tested it with gcc 7.2, and was able to reproduce the NULL pointer dereference, the backtrace looks slightly different this time. I will also test with binutils 2.29, though I doubt that will make any difference. > [ 56.165181] BUG: unable to handle kernel NULL pointer dereference at 0000000000000560 > [ 56.166563] IP: vfs_statfs+0x7c/0xc0 > [ 56.167249] PGD 0 P4D 0 > [ 56.167860] Oops: 0000 [#1] SMP > [ 56.176478] Modules linked in: ipt_MASQUERADE nf_nat_masquerade_ipv4 xt_multiport xt_addrtype iptable_mangle iptable> > [ 56.180227] CPU: 0 PID: 3985 Comm: nfsd Tainted: G O 4.14.0-git-kratos-1 #1 > [ 56.181728] Hardware name: TYAN S5510/S5510, BIOS V2.02 03/12/2013 > [ 56.182729] task: ffff88040c412a00 task.stack: ffffc90002c18000 > [ 56.183629] RIP: 0010:vfs_statfs+0x7c/0xc0 > [ 56.184341] RSP: 0018:ffffc90002c1bb28 EFLAGS: 00010202 > [ 56.185143] RAX: 0000000000000000 RBX: ffffc90002c1bbf0 RCX: 0000000000000020 > [ 56.186085] RDX: 0000000000001801 RSI: 0000000000001801 RDI: 0000000000000000 > [ 56.187066] RBP: ffffc90002c1bbc0 R08: ffffffffffffff00 R09: 00000000000000ff > [ 56.188268] R10: 000000000038be3a R11: ffff880408b18258 R12: 0000000000000000 > [ 56.189336] R13: ffff88040c23ad00 R14: ffff88040b874000 R15: ffffc90002c1bbf0 > [ 56.190444] FS: 0000000000000000(0000) GS:ffff88041fc00000(0000) knlGS:0000000000000000 > [ 56.191876] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 56.192843] CR2: 0000000000000560 CR3: 0000000001e0a002 CR4: 00000000001606f0 > [ 56.193898] Call Trace: > [ 56.194510] nfsd4_encode_fattr+0x201/0x1f90 > [ 56.195267] ? generic_permission+0x12c/0x1a0 > [ 56.196025] nfsd4_encode_getattr+0x25/0x30 > [ 56.196753] nfsd4_encode_operation+0x98/0x1b0 > [ 56.197526] nfsd4_proc_compound+0x2a0/0x5e0 > [ 56.198268] nfsd_dispatch+0xe8/0x220 > [ 56.198968] svc_process_common+0x475/0x640 > [ 56.199696] ? nfsd_destroy+0x60/0x60 > [ 56.200404] svc_process+0xf2/0x1a0 > [ 56.201079] nfsd+0xe3/0x150 > [ 56.201706] kthread+0x117/0x130 > [ 56.202354] ? kthread_create_on_node+0x40/0x40 > [ 56.203100] ret_from_fork+0x25/0x30 > [ 56.203774] Code: d6 89 d6 81 ce 00 04 00 00 f6 c1 08 0f 45 d6 89 d6 81 ce 00 08 00 00 f6 c1 10 0f 45 d6 89 d6 81 ce> > [ 56.206289] RIP: vfs_statfs+0x7c/0xc0 RSP: ffffc90002c1bb28 > [ 56.207110] CR2: 0000000000000560 > [ 56.207763] ---[ end trace d452986a80f64aaa ]--- > On Sat, Nov 11, 2017 at 8:13 AM, Kees Cook wrote: >> >> I'll take a closer look at this and see if I can provide something to >> narrow it down.