linux-kernel - Re: [PATCH] x86/ptrace: Remove questionable TS

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Message-ID: <20160620111243.GA8689@host1.jankratochvil.net>
Date:	Mon, 20 Jun 2016 13:12:43 +0200
From:	Jan Kratochvil <jan.kratochvil@...hat.com>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	Oleg Nesterov <oleg@...hat.com>, Kees Cook <keescook@...omium.org>,
	Borislav Petkov <bp@...en8.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	X86 ML <x86@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Pedro Alves <palves@...hat.com>,
	Roland McGrath <roland@...k.frob.com>
Subject: Re: [PATCH] x86/ptrace: Remove questionable TS_COMPAT usage in ptrace

On Mon, 20 Jun 2016 12:07:56 +0200, Pedro Alves wrote:
> On 06/18/2016 06:02 PM, Andy Lutomirski wrote:
> > Yuck.  I should have dug in to the history.  Why not just
> > unconditionally sign-extend eax when set by a 32-bit tracer?
> 
> No idea.

Roland McGrath knows why he wrote it that way, Cced.

What if eax contains an address in 2GB..4GB range?  I guess currently the
orig_eax check tries to verify %eax cannot contain an address.


Jan