Date: Sat, 4 Apr 2015 16:04:17 +0200
From: Ingo Molnar <mingo@kernel.org>
To: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>, LKML <linux-kernel@vger.kernel.org>,
        Oleg Nesterov <oleg@redhat.com>, Andy Lutomirski <luto@amacapital.net>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Borislav Petkov <bp@alien8.de>, X86 ML <x86@kernel.org>
Subject: Re: sys_execve leaking rbp/rbx/r12-15 to the new process?
Message-ID: <20150404140417.GB22756@gmail.com>
References: <551FEE2F.8050903@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <551FEE2F.8050903@redhat.com>
User-Agent: Mutt/1.5.23 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 775
Lines: 33


* Denys Vlasenko <dvlasenk@redhat.com> wrote:

> We can do this instead:
> 
> ENTRY(stub_execve)
>         CFI_STARTPROC
>         call	sys_execve
> 	testl	%eax, %eax
> 	jz	1f
> 	ret
> 1:      addq	$8, %rsp
> 	xorl	%ebx, %ebx    // maybe create a macro for zeroing these
> 	xorl	%ebp, %ebp    //
> 	xorl	%r12d, %r12d  //
> 	xorl	%r13d, %r13d  //
> 	xorl	%r14d, %r14d  //
> 	xorl	%r15d, %r15d  //

Yeah, call it ZERO_EXTRA_REGS or so.

> Any reason we should not do this change?

Not that I can see - lets try it.

Thanks,

	Ingo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/