Re: [PATCH v11 2/6] x86/entry: Add STACKLEAK erasing the kernel stack at the end of syscalls

From: Kees Cook <keescook@chromium.org>
To: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Popov <alex.popov@linux.com>,
	Ingo Molnar <mingo@kernel.org>, Laura Abbott <labbott@redhat.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Kernel Hardening <kernel-hardening@lists.openwall.com>,
	PaX Team <pageexec@freemail.hu>,
	Brad Spengler <spender@grsecurity.net>,
	Andy Lutomirski <luto@kernel.org>,
	Tycho Andersen <tycho@tycho.ws>,
	Mark Rutland <mark.rutland@arm.com>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Borislav Petkov <bp@alien8.de>,
	Richard Sandiford <richard.sandiford@arm.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	"H . Peter Anvin" <hpa@zytor.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	"Dmitry V . Levin" <ldv@altlinux.org>,
	Emese Revfy <re.emese@gmail.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
	Thomas Garnier <thgarnie@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Alexei Starovoitov <ast@kernel.org>, Josef Bacik <jbacik@fb.com>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Nicholas Piggin <npiggin@gmail.com>,
	Al Viro <viro@zeniv.linux.org.uk>,
	"David S . Miller" <davem@davemloft.net>,
	Ding Tianhong <dingtianhong@huawei.com>,
	David Woodhouse <dwmw@amazon.co.uk>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Dominik Brodowski <linux@dominikbrodowski.net>,
	Juergen Gross <jgross@suse.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Dan Williams <dan.j.williams@intel.com>,
	Mathias Krause <minipli@googlemail.com>,
	Vikas Shivappa <vikas.shivappa@linux.intel.com>,
	Kyle Huey <me@kylehuey.com>,
	Dmitry Safonov <dsafonov@virtuozzo.com>,
	Will Deacon <will.deacon@arm.com>, Arnd Bergmann <arnd@arndb.de>,
	Florian Weimer <fweimer@redhat.com>,
	Boris Lukashev <blukashev@sempervictus.com>,
	X86 ML <x86@kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v11 2/6] x86/entry: Add STACKLEAK erasing the kernel stack at the end of syscalls
Date: Mon, 23 Apr 2018 18:03:51 -0700	[thread overview]
Message-ID: <CAGXu5jJT=SAe5NNKWXu6CXLhX7_C7i4qJ4Znd92jnGxb71UJdA@mail.gmail.com> (raw)
In-Reply-To: <c5a605b8-423f-5e92-5fbe-12cb44a70bd6@linux.intel.com>

On Wed, Apr 18, 2018 at 11:50 AM, Dave Hansen
<dave.hansen@linux.intel.com> wrote:
> On 04/16/2018 11:29 AM, Kees Cook wrote:
>> Dave, Ingo, Linus: how does this look? With the assembly rewritten
>> into C, the entry changes are very small:
>
> The assembly looks very nice to me now.  It is as minimally invasive as
> it can get.  Definitely no objections from me on that part.

Can you give an Acked-by for the x86 parts? Or Ingo?

If this is workable, I'd like to carry it in -next to see if anything
else shakes out...

-Kees

-- 
Kees Cook
Pixel Security