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Date:      Thu, 21 Jul 2005 10:56:54 +0200
From:      =?ISO-8859-1?Q?Eirik_=D8verby?= <ltning@anduin.net>
To:        Kris Kennaway <kris@obsecurity.org>
Cc:        stable@FreeBSD.org, Robert Watson <rwatson@FreeBSD.org>
Subject:   Re: Serious issue with serial console in 5.4
Message-ID:  <00DD4399-4317-4579-82C4-5B64AC3F800B@anduin.net>
In-Reply-To: <20050721050048.GU22430@xor.obsecurity.org>
References:  <20050721050048.GU22430@xor.obsecurity.org>

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On Jul 21, 2005, at 7:00 AM, Kris Kennaway wrote:

> On Mon, Jul 18, 2005 at 11:58:54AM +0200, Eirik ?verby wrote:
>
>> Hi,
>>
>> I reported this before, but I am very surprised that it is still the
>> case:
>>
>> (This is from the last time it happened; this time the box rebooted
>> and cleared the serial console before I had time to cut/paste it.
>>
>>> Fatal trap 12: page fault while in kernel mode
>>> cpuid = 1; apic id = 00
>>> fault virtual address   = 0x1c
>>> fault code              = supervisor write, page not present
>>> instruction pointer     = 0x8:0xc0620b5f
>>> stack pointer           = 0x10:0xdadbd988
>>> frame pointer           = 0x10:0xdadbd994
>>> code segment            = base 0x0, limit 0xfffff, type 0x1b
>>>                       = DPL 0, pres 1, def32 1, gran 1
>>> processor eflags        = interrupt enabled, resume, IOPL = 0
>>> current process         = 51999 (getty)
>>> trap number             = 12
>>> panic: page fault
>>> cpuid = 1
>>> boot() called on cpu#0
>>> Uptime: 66d11h24m50s
>>>
>>
>> The above panic will show up occasionally when logging out from a
>> serial console (i.e. ctrl-D, logout, exit, whatever). This is
>> EXTREMELY BAD, as it will crash an otherwise perfectly healthy box at
>> random - and renders the serial console useless.
>>
>> Robert Watson confirmed this to be an issue on the 10th of April.
>>
>> Anyone??
>>
>
> You might have to wait until 6.0-R since fixing it seems to require
> infrastructure changes that cannot easily be backported to 5.x.

With all due respect - if this is (and I'm assuming it is, because it  
happens on all the servers I'm serial-controlling) an omnipresent  
problem on 5.x, I daresay it should warrant some more attention.  
Having unsafe serial terminal support that can bring down your system  
like that defies much of the point of having serial terminal support  
in the first place.

However, since I seem to be the only one who has noticed this,  
perhaps I'm the last person on earth to routinely use serial terminal  
switches instead of KVM switches to do my admin work?

/Eirik

>
> Kris
>




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