Subject: Re: [regression] nf_iterate(), BUG: unable to handle kernel NULL pointer dereference

From: Ingo Molnar <[email-masked]>
Date: Thu, 24 Jul 2008 13:59:57 +0200

* Ingo Molnar <[email-masked]> wrote:

> here's a new type of crash a -tip testbox triggered today:
> 
> BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
> IP: [<0000000000000000>] 0x0
> PGD 0 
> Oops: 0010 [1] PREEMPT 
> CPU 0 
> Pid: 5331, comm: ssh Not tainted 2.6.26 #21613
> RIP: 0010:[<0000000000000000>]  [<0000000000000000>] 0x0
> RSP: 0018:ffff88003b959a70  EFLAGS: 00010217
> RAX: ffff88003b9ba91c RBX: ffff88003b9baac0 RCX: 0000000000000002
> RDX: ffff88003b9baac0 RSI: 0000000000000014 RDI: ffff88003b9ba3d8
> RBP: ffff88003b959a98 R08: ffff88003e434130 R09: ffff88003b9598b8
> R10: 0000000000002000 R11: 00000000d85507ac R12: ffff88003b9ba3d8
> R13: 0000000000000002 R14: ffff88003e06a020 R15: 0000000000000000
> FS:  00007fb2b7806780(0000) GS:ffffffff80c1c180(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> CR2: 0000000000000000 CR3: 000000003b9e8000 CR4: 00000000000006a0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> Process ssh (pid: 5331, threadinfo ffff88003b958000, task ffff88003b99a000)
> Stack:  ffffffff80777f25 ffff88003b959a98 ffffffff80c24170 ffff88003b959b28
>  0000000000000004 ffff88003b959ae8 ffffffff80733107 ffff88003b959ab8
>  ffff88003b9ba3d8 ffffffff80c1ed60 0000000000000004 ffff88003b9ba3d8
> Call Trace:
>  [<ffffffff80777f25>] ? ipv4_confirm+0x8d/0x122
>  [<ffffffff80733107>] nf_iterate+0x43/0xa5
>  [<ffffffff8074bbb2>] ? ip_finish_output+0x0/0x62
>  [<ffffffff807331cd>] nf_hook_slow+0x64/0xcb
>  [<ffffffff8074bbb2>] ? ip_finish_output+0x0/0x62
>  [<ffffffff8074b63b>] nf_hook_thresh+0x1e/0x20
>  [<ffffffff8074bd44>] ip_output+0xb3/0xc9
>  [<ffffffff8074a27e>] dst_output+0xb/0xd
>  [<ffffffff8074b6ef>] ip_local_out+0x1e/0x22
>  [<ffffffff8074c75c>] ip_queue_xmit+0x2a6/0x321
>  [<ffffffff80241961>] ? sub_preempt_count+0x2d/0x40
>  [<ffffffff8028f239>] ? slob_alloc+0x11b/0x248
>  [<ffffffff8075b85a>] tcp_transmit_skb+0x5ec/0x61b
>  [<ffffffff807122b6>] ? kmalloc+0xc/0xe
>  [<ffffffff8075d7ae>] tcp_connect+0x2a4/0x344
>  [<ffffffff80760cf1>] tcp_v4_connect+0x3cd/0x425
>  [<ffffffff8076bc7d>] inet_stream_connect+0x9a/0x24d
>  [<ffffffff80292988>] ? fget_light+0x38/0x85
>  [<ffffffff8070c60c>] sys_connect+0x68/0x8b
>  [<ffffffff8025dfab>] ? up_read+0x9/0xb
>  [<ffffffff8023727c>] ? do_page_fault+0x55f/0x92f
>  [<ffffffff8022479a>] system_call_fastpath+0x16/0x1b

here's the full bootlog:

 http://redhat.com/~mingo/misc/crash-Thu_Jul_24_13_23_34_CEST_2008.log

kernel is latest -git, v2.6.26-6371-g338b9bb.

	Ingo