linux-kernel - Re: [kernel-hardening] Re: [PATCH] fork: make whole stack

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Date:   Mon, 31 Oct 2016 17:01:14 -0400
From:   Daniel Micay <danielmicay@...il.com>
To:     Florian Weimer <fw@...eb.enyo.de>, Jann Horn <jann@...jh.net>
Cc:     Kees Cook <keescook@...omium.org>,
        kernel-hardening@...ts.openwall.com,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>, Ingo Molnar <mingo@...nel.org>,
        Andy Lutomirski <luto@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [kernel-hardening] Re: [PATCH] fork: make whole stack_canary
 random

> It makes a lot of sense on x86_64 where it means the canary is still
> 56
> bits. Also, you want -fstack-check for protecting again stack
> overflows
> rather than stack *buffer* overflow. SSP won't really help you in that
> regard. Sadly, while -fstack-check now works well in GCC 6 with little
> performance cost, it's not really a complete feature (and Clang impls
> it
> as a no-op!).

Note: talking about userspace after the entropy bit. The kernel doesn't
really -fstack-check, at least in even slightly sane code...
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