linux-kernel - Re: general protection fault in do

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Message-ID: <512487FA.9090102@parallels.com>
Date:	Wed, 20 Feb 2013 12:23:22 +0400
From:	Stanislav Kinsbursky <skinsbursky@...allels.com>
To:	Dave Jones <davej@...hat.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: general protection fault in do_msgrcv  [3.8]

19.02.2013 22:04, Dave Jones пишет:
> general protection fault: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
> Modules linked in: can af_rxrpc binfmt_misc scsi_transport_iscsi ax25 ipt_ULOG decnet nfc appletalk x25 rds ipx p8023 psnap p8022 llc irda crc_ccitt atm lockd sunrpc ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 xt_conntrack nf_conntrack ip6table_filter ip6_tables btusb bluetooth snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_pcm edac_core snd_page_alloc snd_timer microcode rfkill usb_debug serio_raw pcspkr snd soundcore vhost_net r8169 mii tun macvtap macvlan kvm_amd kvm
> CPU 2
> Pid: 887, comm: trinity-child2 Not tainted 3.8.0+ #57 Gigabyte Technology Co., Ltd. GA-MA78GM-S2H/GA-MA78GM-S2H
> RIP: 0010:[<ffffffff812aebba>]  [<ffffffff812aebba>] do_msgrcv+0x22a/0x670
> RSP: 0018:ffff88011892be88  EFLAGS: 00010297
> RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000004000
> RDX: 000000007adea6f6 RSI: 6b6b6b6b6b6b6b6b RDI: ffff8801189ffb60
> RBP: ffff88011892bf68 R08: 0000000000000001 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
> R13: ffff8801189ffc10 R14: ffff8801189ffb60 R15: 6b6b6b6b6b6b6b6b
> FS:  00007f681e955740(0000) GS:ffff88012f200000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f681e846064 CR3: 000000012553d000 CR4: 00000000000007e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> Process trinity-child2 (pid: 887, threadinfo ffff88011892a000, task ffff88010bc82490)
> Stack:
>   ffff88011892beb8 ffff88010bc82490 ffff88010bc82490 ffff88010bc82490
>   ffff8801186d8000 ffffffff812ad5f0 0000000001aba000 ffffffff81c688c0
>   000000007adea6f6 00000000001fffff 0000400046a9467e 6b6b6b6b6b6b6b6b
> Call Trace:
>   [<ffffffff812ad5f0>] ? load_msg+0x180/0x180
>   [<ffffffff810b8395>] ? trace_hardirqs_on_caller+0x115/0x1a0
>   [<ffffffff813347be>] ? trace_hardirqs_on_thunk+0x3a/0x3f
>   [<ffffffff812af015>] sys_msgrcv+0x15/0x20
>   [<ffffffff816a8482>] system_call_fastpath+0x16/0x1b
> Code: 84 14 01 00 00 8b 8d 74 ff ff ff 85 c9 0f 84 52 02 00 00 48 8b 95 60 ff ff ff 48 39 55 80 0f 84 4d 02 00 00 4c 89 bd 78 ff ff ff <4d> 8b 3f 48 ff 45 80 4d 39 ef 75 9a 66 90 48 81 bd 78 ff ff ff
> RIP  [<ffffffff812aebba>] do_msgrcv+0x22a/0x670
>   RSP <ffff88011892be88>
> ---[ end trace d3cc044a84b1d828 ]---
>
> oopsing instruction is..
>
>     0:	4d 8b 3f             	mov    (%r15),%r15
>
> Looks like a use-after-free.
>
> Disassembly of ipc/msg.o shows this happens here..
>
>                  msg = ERR_PTR(-EAGAIN);
>                  tmp = msq->q_messages.next;
>      1537:       4d 8b be b0 00 00 00    mov    0xb0(%r14),%r15
>                  while (tmp != &msq->q_messages) {
>      153e:       4d 8d ae b0 00 00 00    lea    0xb0(%r14),%r13
>      1545:       4d 39 ef                cmp    %r13,%r15
>      1548:       0f 84 5f 03 00 00       je     18ad <do_msgrcv+0x50d>
>      154e:       48 c7 45 80 00 00 00    movq   $0x0,-0x80(%rbp)
>      1555:       00
>      1556:       48 c7 85 78 ff ff ff    movq   $0xfffffffffffffff5,-0x88(%rbp)
>      155d:       f5 ff ff ff
>      1561:       eb 0d                   jmp    1570 <do_msgrcv+0x1d0>
>      1563:       0f 1f 44 00 00          nopl   0x0(%rax,%rax,1)
>                                          }
>                                  } else
>                                          break;
>                                  msg_counter++;
>                          }
>                          tmp = tmp->next;
>      1568:       4d 8b 3f                mov    (%r15),%r15
>                  if (ipcperms(ns, &msq->q_perm, S_IRUGO))
>                          goto out_unlock;
>
>                  msg = ERR_PTR(-EAGAIN);
>                  tmp = msq->q_messages.next;
>                  while (tmp != &msq->q_messages) {
>
> Looks like Stanislav recently changed this code, so problem was likely introduced
> in those changes.
>

Hello.
Is it easy to reproduce? Do you use KVM?
There is a NULL selinux handler bug fix by Stephen Smalley here:
https://lkml.org/lkml/2013/2/6/663

But anyway, this bug fix affects only the case, when MSG_COPY flag is set.

And this is not your case, I suppose?

> 	Dave
>


-- 
Best regards,
Stanislav Kinsbursky
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