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

[Julien Grall <julien.grall@xxxxxxx>]

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?

Cheers,

--
Julien Grall

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