linux-kernel - Re: v2.6.31-rc6: BUG: unable to handle kernel NULL pointer dereference at 0000000000000008

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Message-ID: <a8e1da0908200054t456265b4ta698ba204b5aedc8@mail.gmail.com>
Date:	Thu, 20 Aug 2009 15:54:53 +0800
From:	Dave Young <hidave.darkstar@...il.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	linux-kernel@...r.kernel.org, x86@...nel.org,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Greg Kroah-Hartman <gregkh@...e.de>
Subject: Re: v2.6.31-rc6: BUG: unable to handle kernel NULL pointer 
	dereference at 0000000000000008

On Thu, Aug 20, 2009 at 2:07 PM, Eric W. Biederman<ebiederm@...ssion.com> wrote:
>
> ebiederm@...ssion.com (Eric W. Biederman) writes:
>
>> I'm not certain who I should route this too, but I just had 2.6.31-rc6
>> fall over on me.  I don't know how reproducible this will be but
>> I have a full crash dump if someone is interested in looking into this.
>
> Looks like I was wrong.  This is appears trivial to reproduce,
> I have just reproduced it two more times in a row.  I think
> the problem is pty related.
>
> I was looking into a change in behavior on 2.6.31-rc6 where
> data was being lost, and it appears one variant of my test program
> kills the kernel.
>
> The following program run as an unprivileged user causes a kernel
> panic in about a minute:
>
> aka
>
> while :; do ./KernelTtyTest ; done

The test app failed for me:

read failed: Input/output error
lastbytes: '\r\nprocess_cmd read failed: Interrupted system
call\r\necho _2_\r\n'
Aborted

>
>
> I'm not certain where to start digging into this beyond that.
>
> Eric
>
>
>
>
>
>
>>
>> Eric
>>
>> BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
>> IP: [<ffffffff8105be8b>] run_timer_softirq+0x13a/0x1fa
>> PGD 0
>> Thread overran stack, or stack corrupted
>> Oops: 0002 [#1] SMP
>> last sysfs file: /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq
>> CPU 0
>> Modules linked in: veth macvlan nfsd lockd nfs_acl auth_rpcgss exportfs sco bridge stp bnep l2cap bluetooth sunrpc ipv6 cpufreq_ondemand acpi_cpufreq freq_table ext4 jbd2 crc16 dm_mirror dm_region_hash dm_log dm_multipath dm_mod uinput kvm_intel kvm fuse xt_multiport iptable_nat ip_tables nf_nat x_tables nf_conntrack_ipv4 nf_conntrack nf_defrag_ipv4 tun 8021q ixgbe iTCO_wdt iTCO_vendor_support i2c_i801 mdio e1000e pcspkr serio_raw sg ata_generic pata_acpi ata_piix libata sd_mod scsi_mod ext3 jbd mbcache uhci_hcd ohci_hcd ehci_hcd i915 drm i2c_algo_bit i2c_core video output [last unloaded: microcode]
>> Pid: 0, comm: swapper Not tainted 2.6.31-rc6-172084.2009.AroraKernelBeta.fc11.x86_64 #1 PDSBM
>> RIP: 0010:[<ffffffff8105be8b>]  [<ffffffff8105be8b>] run_timer_softirq+0x13a/0x1fa
>> RSP: 0018:ffff8800017cfe30  EFLAGS: 00010006
>> RAX: ffff8800365b2928 RBX: ffffffff81744e40 RCX: 0000000000000000
>> RDX: ffff8800017cfe50 RSI: 0000000000000246 RDI: 0000000000000000
>> RBP: ffff8800017cfea0 R08: ffff8800017d8c00 R09: ffff8800017cff08
>> R10: 6b40fbe55cdd76b4 R11: ffffffff81744e40 R12: ffff8800017cfe50
>> R13: 0000000000000000 R14: ffffffff81746658 R15: ffffffff81746258
>> FS:  0000000000000000(0000) GS:ffff8800017cc000(0000) knlGS:0000000000000000
>> CS:  0010 DS: 0018 ES: 0018 CR0: 000000008005003b
>> CR2: 0000000000000008 CR3: 0000000001001000 CR4: 00000000000026f0
>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
>> Process swapper (pid: 0, threadinfo ffffffff815b2000, task ffffffff8153f020)
>> Stack:
>>  6b40fbe55cdd76b4 ffff880000000100 ffffffff81746a58 ffffffff81745e58
>> <0> ffff8800365b2928 ffff8800abcd6128 ffffffff81023733 6b40fbe55cdd76b4
>> <0> 6b40fbe55cdd76b4 0000000000000008 0000000000000001 0000000000000100
>> Call Trace:
>>  <IRQ>
>>  [<ffffffff81023733>] ? lapic_next_event+0x23/0x3b
>>  [<ffffffff81056893>] __do_softirq+0xe7/0x1cd
>>  [<ffffffff8100cfac>] call_softirq+0x1c/0x28
>>  [<ffffffff8100e8e5>] do_softirq+0x51/0xae
>>  [<ffffffff810564c6>] irq_exit+0x52/0xa3
>>  [<ffffffff81024080>] smp_apic_timer_interrupt+0x94/0xb9
>>  [<ffffffff8100c973>] apic_timer_interrupt+0x13/0x20
>>  <EOI>
>>  [<ffffffff810143f2>] ? mwait_idle+0x9b/0xcc
>>  [<ffffffff81014394>] ? mwait_idle+0x3d/0xcc
>>  [<ffffffff8100ad4f>] ? enter_idle+0x33/0x49
>>  [<ffffffff8100ae15>] ? cpu_idle+0xb0/0xf3
>>  [<ffffffff81391c75>] ? rest_init+0x79/0x8f
>>  [<ffffffff815bbf8e>] ? start_kernel+0x3dc/0x3fd
>>  [<ffffffff815bb2b4>] ? x86_64_start_reservations+0xbb/0xd6
>>  [<ffffffff815bb3d4>] ? x86_64_start_kernel+0x105/0x128
>> Code: 49 8b 54 1d 20 48 89 55 b8 4c 89 22 49 89 44 1d 20 49 89 44 1d 18 eb 7e 4c 8b 68 18 48 8b 78 20 48 89 43 08 48 8b 08 48 8b 50 08 <48> 89 51 08 48 89 0a 48 c7 40 08 00 02 20 00 48 c7 00 00 00 00
>> RIP  [<ffffffff8105be8b>] run_timer_softirq+0x13a/0x1fa
>>  RSP <ffff8800017cfe30>
>> CR2: 0000000000000008
>
>



-- 
Regards
dave
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