From: Andy Lutomirski <luto@amacapital.net>
To: Borislav Petkov <bp@alien8.de>
Cc: "security@kernel.org" <security@kernel.org>,
Jan Beulich <jbeulich@suse.com>,
Peter Zijlstra <peterz@infradead.org>,
Andrew Cooper <andrew.cooper3@citrix.com>,
X86 ML <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
xen-devel <xen-devel@lists.xen.org>,
stable <stable@vger.kernel.org>,
Andy Lutomirski <luto@kernel.org>,
Sasha Levin <sasha.levin@oracle.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: [PATCH v3 1/3] x86/ldt: Make modify_ldt synchronous
Date: Fri, 24 Jul 2015 21:52:01 -0700 [thread overview]
Message-ID: <CALCETrX=uGdTfmz7KkbVyMKEmwcS4C43L5eNsy65VjNsL=7KJA__45040.6492491767$1437800039$gmane$org@mail.gmail.com> (raw)
In-Reply-To: <20150724152955.GC21441@nazgul.tnic>
On Fri, Jul 24, 2015 at 8:29 AM, Borislav Petkov <bp@alien8.de> wrote:
> Let it stick out:
>
> if (!cpumask_equal(mm_cpumask(current_mm), cpumask_of(smp_processor_id())))
> smp_call_function(flush_ldt, current_mm, 1);
I see your wide terminal and raise you a complete rewrite of that
function. Sigh, why did I assume the old code was the right way to do
it?
>> #endif
>> - }
>> - if (oldsize) {
>> - paravirt_free_ldt(oldldt, oldsize);
>> - if (oldsize * LDT_ENTRY_SIZE > PAGE_SIZE)
>> - vfree(oldldt);
>> - else
>> - put_page(virt_to_page(oldldt));
>> - }
>> - return 0;
>> + preempt_enable();
>> }
>>
>> -static inline int copy_ldt(mm_context_t *new, mm_context_t *old)
>> +static void free_ldt_struct(struct ldt_struct *ldt)
>> {
>> - int err = alloc_ldt(new, old->size, 0);
>> - int i;
>> -
>> - if (err < 0)
>> - return err;
>> -
>> - for (i = 0; i < old->size; i++)
>> - write_ldt_entry(new->ldt, i, old->ldt + i * LDT_ENTRY_SIZE);
>> - return 0;
>> + if (unlikely(ldt)) {
>
> Save an indentation level:
>
> int alloc_size;
>
> if (!ldt)
> return;
>
> alloc_size = sizeof(struct ldt_struct) + ldt->size * LDT_ENTRY_SIZE;
>
Hah¸ we both missed it. This is wrong. (Fix your backport!)
> ...
>
>> + paravirt_free_ldt(ldt->entries, ldt->size);
>> + if (alloc_size > PAGE_SIZE)
>> + vfree(ldt->entries);
>> + else
>> + put_page(virt_to_page(ldt->entries));
I'm not sure this is correct, so I changed it to something obviously
correct (kmalloc/kfree).
>>
>> - fill_ldt(&ldt, &ldt_info);
>> - if (oldmode)
>> - ldt.avl = 0;
>> + if (old_ldt) {
>> + memcpy(new_ldt->entries, old_ldt->entries,
>> + oldsize * LDT_ENTRY_SIZE);
>> + }
>
> Single if-statement doesn't need {} and you don't absolutely need to
> keep 80cols. Just let it stick out.
You read too many of Linus' comments about using wider terminals :)
--Andy
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next prev parent reply other threads:[~2015-07-25 4:52 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <cover.1437592883.git.luto@kernel.org>
2015-07-22 19:23 ` [PATCH v3 1/3] x86/ldt: Make modify_ldt synchronous Andy Lutomirski
2015-07-22 19:23 ` [PATCH v3 2/3] x86/ldt: Make modify_ldt optional Andy Lutomirski
2015-07-22 19:23 ` [PATCH v3 3/3] selftests/x86, x86/ldt: Add a selftest for modify_ldt Andy Lutomirski
[not found] ` <7bfde005b84a90a83bf668a320c7d4ad1b940065.1437592883.git.luto@kernel.org>
2015-07-23 7:13 ` [PATCH v3 2/3] x86/ldt: Make modify_ldt optional Jan Beulich
2015-07-23 10:24 ` Willy Tarreau
[not found] ` <20150723102434.GA2929@1wt.eu>
2015-07-23 23:36 ` Kees Cook
[not found] ` <CAGXu5j+yEWLuxJ9JUGyN7BxME+iOVXfpFgrZ-_2WXUn6A=0dVg@mail.gmail.com>
2015-07-23 23:40 ` Andy Lutomirski
[not found] ` <CALCETrVvfA+_N_tU2LUwvh+2Q_4AExbQkSgW1C4tESAvhY+4Dg@mail.gmail.com>
2015-07-23 23:58 ` Willy Tarreau
[not found] ` <20150723235805.GA3191@1wt.eu>
2015-07-24 0:09 ` Kees Cook
[not found] ` <CAGXu5jJNfMvvdr0q17nBz+HiEJuFa7Kvo=ZPAnb4E7So4W0QOA@mail.gmail.com>
2015-07-24 7:24 ` Willy Tarreau
[not found] ` <20150724072451.GB3293@1wt.eu>
2015-07-24 7:48 ` Willy Tarreau
[not found] ` <049fdbab8ae2ecac1c8b40ecd558e9df45ccd5d3.1437592883.git.luto@kernel.org>
2015-07-22 22:20 ` [PATCH v3 1/3] x86/ldt: Make modify_ldt synchronous Boris Ostrovsky
2015-07-24 6:37 ` Borislav Petkov
2015-07-24 15:29 ` Borislav Petkov
[not found] ` <55B01745.4010702@oracle.com>
2015-07-25 4:13 ` Boris Ostrovsky
[not found] ` <55B30CE3.2010902@oracle.com>
2015-07-25 4:58 ` Andy Lutomirski
[not found] ` <20150724152955.GC21441@nazgul.tnic>
2015-07-25 4:52 ` Andy Lutomirski [this message]
[not found] ` <CALCETrX=uGdTfmz7KkbVyMKEmwcS4C43L5eNsy65VjNsL=7KJA@mail.gmail.com>
2015-07-25 8:37 ` Borislav Petkov
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