Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Sat, 28 Oct 2017 09:47:30 +0100
From: Russell King - ARM Linux <>
To: Will Deacon <>
Cc: Mark Rutland <>, Kees Cook <>,,
	Catalin Marinas <>,, Laura Abbott <>,
Subject: Re: [RFC PATCH 0/2] arm64: optional paranoid __{get,put}_user checks

On Fri, Oct 27, 2017 at 04:41:13PM +0100, Will Deacon wrote:
> Probably a stupid question, but why not just move the access_ok check
> into __{get,put}_user and remove it from {get,put}_user? We can also
> then move the uaccess_{enable,disable}_not_uao calls out from the __
> variants so that we can implement user_access_{begin,end}.

The intent of __{get,put}_user() is to have a fast accessor compared
to {get,put}_user() which does all the full checks.

However, with the uaccess stuff we have now by default, I don't think
it makes much sense - maybe we're better off using copy_{to,from}_user()
in those code paths and fixing up the struct in kernel space rather than

I suspect that if we do have the full checks in __{get,put}_user() that
makes the case stronger for doing that - and maybe killing the __
accessors entirely.

Take a look at kernel/signal.c to see a typical usage of the __

RMK's Patch system:
FTTC broadband for 0.8mile line in suburbia: sync at 8.8Mbps down 630kbps up
According to 8.21Mbps down 510kbps up

Powered by blists - more mailing lists

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.