Re: [Xen-devel] [PATCH] x86: polish __{get,put}_user_{,no}check()

[Julien Grall <julien.grall@xxxxxxx>]

Hi Andrew,

On 04/05/17 18:52, Andrew Cooper wrote:
> On 04/05/17 09:52, Julien Grall wrote:
> > Hi,
> >
> > On 02/05/17 14:23, Jan Beulich wrote:
> > > The primary purpose is correcting a latent bug in __get_user_check()
> > > (the macro has no active user at present): The access_ok() check should
> > > be before the actual access, or else any PV guest could initiate MMIO
> > > reads with side effects.
> > >
> > > Clean up all four macros at once:
> > > - all arguments evaluated exactly once
> > > - build the "check" flavor using the "nocheck" ones, instead of open
> > >   coding them
> > > - "int" is wide enough for error codes
> > > - name local variables without using underscores as prefixes
> > > - avoid pointless parentheses
> > > - add blanks after commas separating parameters or arguments
> > > - consistently use tabs for indentation
> > >
> > > Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> > > ---
> > > This corrects the code which would have resulted in an XSA on Xen 4.2
> > > and older, if those were still security supported. For that reason I at
> > > least want to explore whether this is a change we want to take for 4.9.
> > Andrew, do you have any opinion to get this patch in Xen 4.9?
> It should go in.
Release-acked-by: Julien grall <julien.grall@xxxxxxx>

Cheers,

--
Julien Grall

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