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Date: Mon, 13 Nov 2017 14:48:38 -0800
From: Patrick McLean <chutzpah@...too.org>
To: Linus Torvalds <torvalds@...ux-foundation.org>,
Kees Cook <keescook@...omium.org>
Cc: Emese Revfy <re.emese@...il.com>, Al Viro <viro@...iv.linux.org.uk>,
Bruce Fields <bfields@...hat.com>, "Darrick J. Wong"
<darrick.wong@...cle.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Linux NFS Mailing List <linux-nfs@...r.kernel.org>,
stable <stable@...r.kernel.org>,
Thorsten Leemhuis <regressions@...mhuis.info>,
"kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>
Subject: Re: [nfsd4] potentially hardware breaking regression in 4.14-rc and
4.13.11
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 <keescook@...omium.org> wrote:
>>
>> I'll take a closer look at this and see if I can provide something to
>> narrow it down.
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