Re: [Xen-devel] [PATCH] viridian: make viridian_time_domain_freeze() safe to call...

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Roger Pau Monne <roger.pau@xxxxxxxxxx>
> Sent: 21 August 2019 09:52
> To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx; Jan Beulich <jbeulich@xxxxxxxx>; Andrew 
> Cooper
> <Andrew.Cooper3@xxxxxxxxxx>; Wei Liu <wl@xxxxxxx>
> Subject: Re: [PATCH] viridian: make viridian_time_domain_freeze() safe to 
> call...
> 
> On Wed, Aug 21, 2019 at 09:22:58AM +0100, Paul Durrant wrote:
> > ...on a partially destroyed domain.
> >
> > viridian_time_domain_freeze() and viridian_time_vcpu_freeze() rely
> > (respectively) on the dynamically allocated per-domain and per-vcpu viridian
> > areas [1], which are freed during domain_relinquish_resources().
> > Because arch_domain_pause() can call viridian_domain_time_freeze() this
> > can lead to host crashes if e.g. a XEN_DOMCTL_pausedomain is issued after
> > domain_relinquish_resources() has run.
> >
> > To prevent such crashes, this patch adds a check of is_dying into
> > viridian_time_domain_freeze(), and viridian_time_domain_thaw() which is
> > similarly vulnerable to indirection into freed memory.
> >
> > NOTE: The patch also makes viridian_time_vcpu_freeze/thaw() static, since
> >       they have no callers outside of the same source module.
> >
> > [1] See commit e7a9b5e72f26 "viridian: separately allocate domain and vcpu
> >     structures".
> >
> > Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
> 
> Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> 
> Note you could also drop the viridian_ prefix to the now static
> functions.
> 

Yeah, they could be dropped. May be a friendly committer could do it? :-)

  Paul

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