Re: [Xen-devel] [BUG] double fault for sale ;)

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 29 May 2006, at 16:00, Gerd Hoffmann wrote:

> I'm busy rewriting the domain builder code a bit, to restruct the code
> and make it better usable for other tasks than directly booting a
> domain.  While testing these bits I trapped into that one:
>
> (XEN) CPU:    1
> (XEN) EIP:    e008:[<ff137512>] get_page_type+0x12/0x63d
> (XEN) EFLAGS: 00010296
> (XEN) CR3:    00000000
> (XEN) eax: 33030001   ebx: ff1c1080   ecx: ff1d4080   edx: ff1d4080
> (XEN) esi: 0000001a   edi: ffbf5fac   ebp: ffbf502c   esp: ffbf4f84
> (XEN) ds: e010   es: e010   fs: 0000   gs: 0000   ss: e010
> (XEN) ************************************
> (XEN) CPU1 DOUBLE FAULT -- system shutdown
> (XEN) System needs manual reset.
> (XEN) ************************************
>
> I think even Domain-0 shouldn't be able to crash xen like this, no?
Looks like a stack overflow, since the stack pointer is in an "even" 
page which is guard page when running a debug build of Xen. Maybe you 
could hack up some code to get a rough back trace (round the crashing 
stack pointer up to a page boundary then scan a whole page for text 
addresses)?
Either need to fix some large stack frame or make the stack larger. 
Probably the former.
 -- Keir


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