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From: Peter Zijlstra <peterz@infradead.org>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Ingo Molnar <mingo@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [RFC][PATCH] x86: Verify access_ok() context
Date: Tue, 22 Nov 2016 20:37:20 +0100	[thread overview]
Message-ID: <20161122193720.GA3045@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <CALCETrW2mdAo59OW0+VfqTg8OAXe9qmiq23dex62a1ry0u2=Vw@mail.gmail.com>

On Tue, Nov 22, 2016 at 09:28:01AM -0800, Andy Lutomirski wrote:
> On Tue, Nov 22, 2016 at 1:57 AM, Peter Zijlstra <peterz@infradead.org> wrote:

> > +#define access_ok(type, addr, size)                                    \
> > +({                                                                     \
> > +       WARN_ON_ONCE(!in_task());                                       \
> 
> Should this be guarded by some debug option?  This may hurt
> performance on production systems quite a bit.

I suspected something like that; any suitable CONFIG come to mind? I'm
somewhat reluctant to create yet another one for this.

CONFIG_DEBUG_VM seems somehow inappropriate.

> For what it's worth, I think ARM recently started saving the address
> limit and resetting it to USER_DS on NMI entry.

Up to them of course, but doing less on interrupt entry/exit seems
better.

  reply	other threads:[~2016-11-22 19:37 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-11-22  9:57 [RFC][PATCH] x86: Verify access_ok() context Peter Zijlstra
2016-11-22 17:28 ` Andy Lutomirski
2016-11-22 19:37   ` Peter Zijlstra [this message]
2016-11-22 19:42     ` Linus Torvalds
2016-12-05 10:27       ` Peter Zijlstra
2017-01-16 20:27         ` David Smith
2017-01-16 21:14           ` Thomas Gleixner
2017-01-18 22:16             ` David Smith
2017-01-19  0:19               ` Andy Lutomirski
2017-01-19 15:37                 ` David Smith
2017-01-20  8:24                 ` Peter Zijlstra
2017-01-20  8:50                   ` Thomas Gleixner
2017-01-19 18:12               ` Thomas Gleixner
2017-01-19 20:22                 ` Frank Ch. Eigler
2017-01-19 20:50                   ` Thomas Gleixner
2017-01-19 21:27                     ` Frank Ch. Eigler
2017-01-19 22:20                       ` Peter Zijlstra
2017-01-19 23:04                       ` Thomas Gleixner

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