Re: [Xen-devel] [PATCH] xen: arm: fully implement multicall interface.

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 03/28/2014 02:45 PM, Ian Campbell wrote:

> My feeling is that any (exploitable or otherwise) issue due to this
> would be due to lack of proper error checking in the hypercall, and
> would be equally accessible by a 64-bit guest.

I don't think it's exploitable. IHMO, the main point is to give a useful
debug to the user rather than an obscure error message because the given
pointer is invalid (perhaps by mistake).

> I'm considering whether to add an #ifndef NDEBUG check here which will
> reject a multicall from a 32-bit guest where any of the arguments
> (arm_hypercall_table[nr].nr_args) are non-zero in their top 32-bit. I
> can't decide whether -EINVAL or domain_kill() would be more appropriate.
> I'm actually leaning towards the latter.
> 
> Thoughts?

Killing the domain is a bit tough. But it seems that all failures in
trap.c result to crash the domain.

Regards,

-- 
Julien Grall

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