linux-kernel - Re: [PATCH v4 15/17] x86/traps: Fixup general protection faults caused by UMIP

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CALCETrX-b1Pjz=bFfj+YFk=Fgy5FKTpAYig__zF=GTn4VXNf4w@mail.gmail.com>
Date:   Fri, 24 Feb 2017 11:11:30 -0800
From:   Andy Lutomirski <luto@...capital.net>
To:     Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andy Lutomirski <luto@...nel.org>,
        Borislav Petkov <bp@...e.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Brian Gerst <brgerst@...il.com>,
        Chris Metcalf <cmetcalf@...lanox.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Liang Z Li <liang.z.li@...el.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Huang Rui <ray.huang@....com>, Jiri Slaby <jslaby@...e.cz>,
        Jonathan Corbet <corbet@....net>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Paul Gortmaker <paul.gortmaker@...driver.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Chen Yucong <slaoub@...il.com>,
        Alexandre Julliard <julliard@...ehq.org>,
        Stas Sergeev <stsp@...t.ru>, Fenghua Yu <fenghua.yu@...el.com>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>,
        Shuah Khan <shuah@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        X86 ML <x86@...nel.org>, linux-msdos@...r.kernel.org,
        wine-devel@...ehq.org, Tony Luck <tony.luck@...el.com>
Subject: Re: [PATCH v4 15/17] x86/traps: Fixup general protection faults
 caused by UMIP

On Thu, Feb 23, 2017 at 2:15 PM, Ricardo Neri
<ricardo.neri-calderon@...ux.intel.com> wrote:
> On Thu, 2017-02-23 at 10:27 +0100, Peter Zijlstra wrote:
>> On Wed, Feb 22, 2017 at 10:37:04PM -0800, Ricardo Neri wrote:
>> > @@ -492,6 +493,9 @@ do_general_protection(struct pt_regs *regs, long error_code)
>> >     RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
>> >     cond_local_irq_enable(regs);
>> >
>> > +   if (user_mode(regs) && (fixup_umip_exception(regs) == true))
>> > +           return;
>>
>> I'm thinking
>>
>>       if (user_mode(regs) && fixup_umip_exception(regs))
>>               return;
>>
>> is actually easier to read.
>
> In a previous version Andy Lutomirsky suggested that
>         if (user_mode(regs) && (fixup_umip_exception(regs) == 0))
>
> was easier to read :). Although at the time fixup_umip_exception
> returned a numeric value. Now it only returns true/false for
> successful/failed emulation. If with true/false not comparing to true
> makes it easier to read, I will make the change.

I think == true is silly :)

--Andy