MIME-Version: 1.0
In-Reply-To: <CALCETrUtqOmFjj6ie8vaCuM6SX91BNotA-gwf90bUY9hj_qD1g@mail.gmail.com>
References: <20170317115924.GA82960@inn.lkp.intel.com> <CA+55aFwx5D1hSaW6ac3D=30cY7=2i4cPmGn9zB-1a8ywpau3cw@mail.gmail.com>
 <CA+55aFx2ArTYrdd10A07Y-cD==7yCNE-2kZQcMeAoZKnxFCO2Q@mail.gmail.com>
 <CA+55aFzYxqhLoDcepjt4Z3uLRBNdAg5Ou25Uj9vzZO2RfaVrDQ@mail.gmail.com> <CALCETrUtqOmFjj6ie8vaCuM6SX91BNotA-gwf90bUY9hj_qD1g@mail.gmail.com>
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Fri, 17 Mar 2017 12:36:22 -0700
Message-ID: <CA+55aFxrbQpisKU1ZuymdpYgSdxSUZ98k-fXjHZy9G9DwCXtgA@mail.gmail.com>
Subject: Re: [x86] 45fc8757d1: BUG:unable_to_handle_kernel
To: Andy Lutomirski <luto@kernel.org>
Cc: kernel test robot <xiaolong.ye@intel.com>,
        Thomas Garnier <thgarnie@google.com>, Ingo Molnar <mingo@kernel.org>,
        Alexander Potapenko <glider@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        Borislav Petkov <bp@suse.de>, Chris Wilson <chris@chris-wilson.co.uk>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Jiri Kosina <jikos@kernel.org>, Joerg Roedel <joro@8bytes.org>,
        Jonathan Corbet <corbet@lwn.net>, Josh Poimboeuf <jpoimboe@redhat.com>,
        Juergen Gross <jgross@suse.com>, Kees Cook <keescook@chromium.org>,
        Len Brown <len.brown@intel.com>, Lorenzo Stoakes <lstoakes@gmail.com>,
        "Luis R . Rodriguez" <mcgrof@kernel.org>,
        Matt Fleming <matt@codeblueprint.co.uk>,
        Michal Hocko <mhocko@suse.com>, Paolo Bonzini <pbonzini@redhat.com>,
        Paul Gortmaker <paul.gortmaker@windriver.com>,
        Pavel Machek <pavel@ucw.cz>, Peter Zijlstra <peterz@infradead.org>,
        =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        "Rafael J . Wysocki" <rjw@rjwysocki.net>,
        Rusty Russell <rusty@rustcorp.com.au>,
        Stanislaw Gruszka <sgruszka@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Tim Chen <tim.c.chen@linux.intel.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>, zijun_hu <zijun_hu@htc.com>,
        LKML <linux-kernel@vger.kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
        tipbuild@zytor.com, LKP <lkp@01.org>
Content-Type: text/plain; charset=UTF-8
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 505
Lines: 17

On Fri, Mar 17, 2017 at 11:20 AM, Andy Lutomirski <luto@kernel.org> wrote:
>
> I can easily imagine that breaking WINE or DOSEMU because it'll affect
> the LDT, too.

Can they even *read* the LDT contents, though? The whole accessed bit
doesn't show up in 'struct user_desc', so you can neither set it nor
read it.

> How about this:

I don't think that's _wrong_, but..

I'd really rather just do it in fill_ldt() itself, unless you can
explain how it would be visible to anybody..

               Linus