linux-kernel - Re: [PATCH 3.16 56/76] x86/syscall: Sanitize syscall table de-references under speculation

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Message-ID: <1521421160.2495.188.camel@decadent.org.uk>
Date:   Mon, 19 Mar 2018 00:59:20 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     Jiri Slaby <jslaby@...e.cz>, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Cc:     akpm@...ux-foundation.org,
        Jinpu Wang <jinpu.wang@...fitbricks.com>,
        kernel-hardening@...ts.openwall.com,
        Andy Lutomirski <luto@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Jan Beulich <JBeulich@...e.com>, alan@...ux.intel.com,
        Thomas Gleixner <tglx@...utronix.de>,
        Dan Williams <dan.j.williams@...el.com>,
        gregkh@...uxfoundation.org, linux-arch@...r.kernel.org
Subject: Re: [PATCH 3.16 56/76] x86/syscall: Sanitize syscall table
 de-references under speculation

On Mon, 2018-03-12 at 08:32 +0100, Jiri Slaby wrote:
> On 03/12/2018, 04:06 AM, Ben Hutchings wrote:
> > In 3.16 the x86_32 syscall table lookup is also written in assembly.
> > So I've taken Jiri's version and added similar masking in entry_32.S,
> > using edx as the temporary.  edx is clobbered by SAVE_REGS and seems
> > to be free at this point.
> 
> I don't know the state in 3.16, but in 3.12, I had to fix the 32bit
> entry on 64bit in arch/x86/ia32/ia32entry.S (ia32_sysenter_target &
> others) too.

Thank you, yes I need to fix them in 3.16 too.  I also failed to use
retpolines there.

Ben.

-- 
Ben Hutchings
The first rule of tautology club is the first rule of tautology club.


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