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Message-ID: <CAGXu5jJFNymPhRp=1Zp829-_wmT2XwzR0Lej2hy_CExQrG1Y5g@mail.gmail.com>
Date: Wed, 7 Sep 2016 10:25:58 -0700
From: Kees Cook <keescook@...omium.org>
To: Paul McKenney <paulmck@...ux.vnet.ibm.com>
Cc: kernel test robot <xiaolong.ye@...el.com>, LKP <lkp@...org>,
LKML <linux-kernel@...r.kernel.org>,
Rik van Riel <riel@...hat.com>,
Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [list] 8052ce2d97: WARNING: CPU: 0 PID: 1 at lib/list_debug.c:60 __list_del_entry+0x4d/0x71
On Wed, Sep 7, 2016 at 12:31 AM, Paul E. McKenney
<paulmck@...ux.vnet.ibm.com> wrote:
> On Tue, Sep 06, 2016 at 11:49:04AM -0400, Kees Cook wrote:
>> On Sun, Sep 4, 2016 at 5:48 AM, Paul E. McKenney
>> <paulmck@...ux.vnet.ibm.com> wrote:
>> > On Sun, Sep 04, 2016 at 08:35:40AM +0800, kernel test robot wrote:
>> >>
>> >> FYI, we noticed the following commit:
>> >>
>> >> https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2016.08.19a
>> >> commit 8052ce2d9771ab5a818307f3abbaf33bba82a631 ("list: Split list_add() debug checking into separate function")
>> >>
>> >> in testcase: boot
>> >>
>> >> on test machine: qemu-system-i386 -enable-kvm -m 360M
>> >>
>> >> caused below changes:
>> >
>> > Hello, Kees,
>> >
>> > Looks like your change might have actually found a bug. ;-)
>> >
>> > How would you like to handle this?
>>
>> We should fix the bug! :)
>
> But of course...
>
> The question is whether I am considered to be fully responsible for
> chasing down any bugs that arise. It is looking like I am, in which
> case I must defer this patch to the 4.10 merge window. Things are a
> bit crazy now due to prior overcommitments...
I'm going to double-check the code, but the changes I made shouldn't
have changed any of the logical checks under CONFIG_DEBUG_LIST... just
the manifestation of WARN vs BUG. So, since both this and the BPF RCU
bug have appeared, something has changed... I will go digging...
-Kees
>
> Yes, yes, they will be crazy then as well, but this would be higher
> on the priority list.
>
> Thanx, Paul
>
>> >> +------------------------------------------------------------+------------+------------+
>> >> | | 0a33d912a3 | 8052ce2d97 |
>> >> +------------------------------------------------------------+------------+------------+
>> >> | boot_successes | 0 | 0 |
>> >> | boot_failures | 211 | 18 |
>> >> | WARNING:at_lib/list_debug.c:#__list_del_entry | 211 | 18 |
>> >> | calltrace:init | 209 | 18 |
>> >> | WARNING:at_lib/list_debug.c:#__list_add | 209 | |
>> >> | calltrace:i8042_init | 209 | 17 |
>> >> | calltrace:SyS_reboot | 192 | 4 |
>> >> | EIP_is_at__mutex_unlock_slowpath | 29 | |
>> >> | Kernel_panic-not_syncing:softlockup:hung_tasks | 138 | |
>> >> | BUG:workqueue_lockup-pool_cpus=#flags=#nice=#stuck_for#s | 56 | |
>> >> | EIP_is_at_lock_release | 7 | |
>> >> | EIP_is_at_lock_acquire | 28 | |
>> >> | EIP_is_at_raw_spin_unlock_irq | 30 | |
>> >> | EIP_is_at_mutex_lock_nested | 21 | |
>> >> | EIP_is_at_lock_is_held | 10 | |
>> >> | EIP_is_at_device_shutdown | 3 | |
>> >> | EIP_is_at___might_sleep | 5 | |
>> >> | EIP_is_at__list_del_entry | 4 | 1 |
>> >> | EIP_is_at_get_device | 1 | |
>> >> | BUG:unable_to_handle_kernel | 7 | 5 |
>> >> | Oops | 7 | 5 |
>> >> | calltrace:SyS_ipc | 4 | 4 |
>> >> | Kernel_panic-not_syncing:Fatal_exception | 7 | 5 |
>> >> | EIP_is_at_pm_runtime_barrier | 1 | |
>> >> | EIP_is_at_lock_acquired | 1 | |
>> >> | EIP_is_at__might_sleep | 1 | |
>> >> | BUG:workqueue_lockup-pool_cpus=#-#flags=#nice=#stuck_for#s | 1 | |
>> >> | WARNING:at_arch/x86/mm/dump_pagetables.c:#note_page | 26 | |
>> >> | calltrace:mark_rodata_ro | 26 | |
>> >> | WARNING:at_lib/list_debug.c:#__list_add_valid | 0 | 17 |
>> >> | calltrace:serio_handle_event | 0 | 17 |
>> >> | calltrace:userio_misc_init | 0 | 17 |
>> >> | calltrace:mousedev_init | 0 | 17 |
>> >> | calltrace:evdev_init | 0 | 17 |
>> >> | calltrace:cmos_init | 0 | 17 |
>> >> | calltrace:test_init | 0 | 17 |
>> >> | calltrace:pca_isa_driver_init | 0 | 17 |
>> >> | calltrace:vim2m_init | 0 | 17 |
>> >> | calltrace:fm_drv_init | 0 | 17 |
>> >> | calltrace:test_power_init | 0 | 17 |
>> >> | calltrace:raid#_init | 0 | 17 |
>> >> | calltrace:dm_init | 0 | 17 |
>> >> | calltrace:vhci_init | 0 | 17 |
>> >> | calltrace:dcdrbu_init | 0 | 17 |
>> >> | calltrace:dcdbas_init | 0 | 17 |
>> >> | calltrace:uhid_init | 0 | 17 |
>> >> | calltrace:vhost_net_init | 0 | 17 |
>> >> | calltrace:dummy_stm_init | 0 | 17 |
>> >> | calltrace:stm_heartbeat_init | 0 | 17 |
>> >> | calltrace:binder_init | 0 | 17 |
>> >> | calltrace:teql_init | 0 | 17 |
>> >> | calltrace:ipip_init | 0 | 17 |
>> >> | calltrace:ipgre_init | 0 | 17 |
>> >> | calltrace:sit_init | 0 | 17 |
>> >> | calltrace:ip6_tunnel_init | 0 | 17 |
>> >> | calltrace:ip6gre_init | 0 | 17 |
>> >> | calltrace:irlan_init | 0 | 17 |
>> >> | calltrace:pm_qos_power_init | 0 | 17 |
>> >> | calltrace:ubi_init | 0 | 17 |
>> >> | calltrace:SyS_setsockopt | 0 | 2 |
>> >> | calltrace:SyS_socketcall | 0 | 2 |
>> >> | WARNING:at_include/linux/kref.h:#kobject_get | 0 | 4 |
>> >> | WARNING:at_kernel/locking/lockdep.c:#__lock_acquire | 0 | 4 |
>> >> | BUG:kernel_hang_in_test_stage | 0 | 4 |
>> >> | calltrace:fw_cfg_sysfs_init | 0 | 7 |
>> >> +------------------------------------------------------------+------------+------------+
>> >>
>> >>
>> >>
>> >> [ 152.680291] g_acm_ms usbip-vudc.0: failed to start g_acm_ms: -22
>> >> [ 152.689209] usbip-vudc: probe of usbip-vudc.0 failed with error -22
>> >> [ 152.698509] ------------[ cut here ]------------
>> >> [ 152.709786] WARNING: CPU: 0 PID: 1 at lib/list_debug.c:60 __list_del_entry+0x4d/0x71
>> >> [ 152.722785] list_del corruption. next->prev should be cc0230d4, but was 6b6b6b6b
>>
>> That's the poison value, so this is a remove-after-remove bug?
>>
>> >> [ 152.732828] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.8.0-rc1-00033-g8052ce2 #1
>> >> [ 152.742576] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014
>> >> [ 152.754081] 00000000 00200246 c0033e78 c13c456b c0033ea4 c13e72ac c0033e90 c103fd02
>> >> [ 152.765720] 0000003c 6b6b6b6b cc0230d4 cc02300c c0033eac c103fd41 00000009 00000000
>> >> [ 152.776864] c0033ea4 c1f7bc14 c0033ec0 c0033ecc c13e72ac c1f7bace 0000003c c1f7bc14
>> >> [ 152.788472] Call Trace:
>> >> [ 152.791964] [<c13c456b>] dump_stack+0x75/0xa9
>> >> [ 152.797835] [<c13e72ac>] ? __list_del_entry+0x4d/0x71
>> >> [ 152.804221] [<c103fd02>] __warn+0xad/0xc4
>> >> [ 152.809694] [<c103fd41>] warn_slowpath_fmt+0x28/0x2d
>> >> [ 152.816501] [<c13e72ac>] __list_del_entry+0x4d/0x71
>> >> [ 152.822946] [<c15027a8>] device_pm_remove+0x2b/0x5a
>> >> [ 152.829560] [<c14f6317>] device_del+0x134/0x19a
>> >> [ 152.835558] [<c14f5c38>] ? dev_set_name+0x14/0x16
>> >> [ 152.842135] [<c14f9d7c>] platform_device_del+0x16/0x5d
>> >> [ 152.848909] [<c2207515>] init+0xe5/0x112
>> >> [ 152.854149] [<c2207430>] ? usbip_host_init+0xe5/0xe5
>>
>> What device is this? Looks like it's being removed right at init time??
>>
>> >> [ 152.860796] [<c21cec35>] do_one_initcall+0x7e/0x101
>> >> [ 152.867316] [<c10564b7>] ? parse_args+0x190/0x265
>> >> [ 152.873497] [<c21ced88>] ? kernel_init_freeable+0xd0/0x174
>> >> [ 152.880923] [<c21ceda4>] kernel_init_freeable+0xec/0x174
>> >> [ 152.887499] [<c1be421b>] kernel_init+0x8/0xd0
>> >> [ 152.893658] [<c1bec3ae>] ret_from_kernel_thread+0xe/0x30
>> >> [ 152.900759] [<c1be4213>] ? rest_init+0x111/0x111
>> >> [ 152.907334] ---[ end trace 2003739b08d25430 ]---
>> >> [ 152.920040] ------------[ cut here ]------------
>>
>> -Kees
>>
>>
>> --
>> Kees Cook
>> Nexus Security
>>
>
--
Kees Cook
Nexus Security
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