linux-kernel - Re: [PATCH v3 1/3] x86/ldt: Make modify

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Message-ID: <20150725083727.GB3427@nazgul.tnic>
Date:	Sat, 25 Jul 2015 10:37:27 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	Andy Lutomirski <luto@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	"security@...nel.org" <security@...nel.org>,
	X86 ML <x86@...nel.org>, Sasha Levin <sasha.levin@...cle.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Boris Ostrovsky <boris.ostrovsky@...cle.com>,
	Andrew Cooper <andrew.cooper3@...rix.com>,
	Jan Beulich <jbeulich@...e.com>,
	xen-devel <xen-devel@...ts.xen.org>,
	stable <stable@...r.kernel.org>
Subject: Re: [PATCH v3 1/3] x86/ldt: Make modify_ldt synchronous

On Fri, Jul 24, 2015 at 09:52:01PM -0700, Andy Lutomirski wrote:
> I see your wide terminal and raise you a complete rewrite of that
> function.  Sigh, why did I assume the old code was the right way to do
> it?

That's a mostly wrong assumption, as experience proves.

> Hah¸ we both missed it.  This is wrong.  (Fix your backport!)

Yikes:

	alloc_size = size * LDT_ENTRY_SIZE;

But hey, I made you spot it, still! :-)

Done.

> I'm not sure this is correct, so I changed it to something obviously
> correct (kmalloc/kfree).

Someone thought she won't get contiguous memory from kmalloc(). But how
big can alloc_size be to fail...

> You read too many of Linus' comments about using wider terminals :)

Nah, I'm just trying to put back some sanity in that 80 cols rule which,
even you, think is a hard one. And I say, keep 80 cols but sanity can
override it if what 80 cols produces, is crap.

I trust you're sane enough to apply that and not think C++ or java
wankery. Woahahahah...

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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