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

Hi Andrew,

On 04/05/17 18:52, Andrew Cooper wrote:
On 04/05/17 09:52, Julien Grall wrote:

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>


Julien Grall

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