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From: Kees Cook <keescook@chromium.org>
To: "Reshetova, Elena" <elena.reshetova@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>,
	Kernel Hardening <kernel-hardening@lists.openwall.com>,
	Andy Lutomirski <luto@amacapital.net>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Jann Horn <jannh@google.com>,
	"Perla, Enrico" <enrico.perla@intel.com>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Greg KH <gregkh@linuxfoundation.org>
Subject: Re: [RFC PATCH] x86/entry/64: randomize kernel stack offset upon syscall
Date: Thu, 4 Apr 2019 10:03:58 -0700	[thread overview]
Message-ID: <CAGXu5j+05tZUOuka2YQy+5WPvVwHBrM-YEeto1iLzz2shCnANQ@mail.gmail.com> (raw)
In-Reply-To: <2236FBA76BA1254E88B949DDB74E612BA4C3BA7F@IRSMSX102.ger.corp.intel.com>

On Thu, Apr 4, 2019 at 4:41 AM Reshetova, Elena
<elena.reshetova@intel.com> wrote:
> What I still don't fully understand here (due to my little knowledge of
> compilers) and afraid of is that the asm code that alloca generates (see my version)
> and the alignment might differ on the different targets, etc.

I guess it's possible, but for x86_64, since appears to be consistent.

> If you tried it on yours, can you send me the asm code that it produced for you?
> Is it different from mine?

You can compare compiler outputs here. Here's gcc vs clang for this code:
https://godbolt.org/z/WJSbN8
You can adjust compiler versions, etc.

-- 
Kees Cook

  reply	other threads:[~2019-04-04 17:03 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-29  8:13 [RFC PATCH] x86/entry/64: randomize kernel stack offset upon syscall Elena Reshetova
2019-04-03 21:17 ` Kees Cook
2019-04-04 11:41   ` Reshetova, Elena
2019-04-04 17:03     ` Kees Cook [this message]
2019-04-05 10:14       ` Reshetova, Elena
2019-04-05 13:14         ` Andy Lutomirski
  -- strict thread matches above, loose matches on Subject: below --
2019-03-20  7:27 Elena Reshetova
2019-03-20  7:29 ` Reshetova, Elena

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