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Message-ID: <CABCJKue=yZqe23DYg3_WyiSKhxXS+GXe+3skhvYon4ytkfH+XA@mail.gmail.com>
Date: Mon, 4 Nov 2019 15:42:09 -0800
From: Sami Tolvanen <samitolvanen@...gle.com>
To: Mark Rutland <mark.rutland@....com>
Cc: Will Deacon <will@...nel.org>, Catalin Marinas <catalin.marinas@....com>, 
	Steven Rostedt <rostedt@...dmis.org>, Masami Hiramatsu <mhiramat@...nel.org>, 
	Ard Biesheuvel <ard.biesheuvel@...aro.org>, Dave Martin <Dave.Martin@....com>, 
	Kees Cook <keescook@...omium.org>, Laura Abbott <labbott@...hat.com>, 
	Marc Zyngier <maz@...nel.org>, Nick Desaulniers <ndesaulniers@...gle.com>, Jann Horn <jannh@...gle.com>, 
	Miguel Ojeda <miguel.ojeda.sandonis@...il.com>, 
	Masahiro Yamada <yamada.masahiro@...ionext.com>, 
	clang-built-linux <clang-built-linux@...glegroups.com>, 
	Kernel Hardening <kernel-hardening@...ts.openwall.com>, 
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 10/17] arm64: disable kretprobes with SCS

On Mon, Nov 4, 2019 at 9:05 AM Mark Rutland <mark.rutland@....com> wrote:
> I'm a bit confused as to why that's the case -- could you please
> elaborate on how this is incompatible?
>
> IIUC kretrobes works by patching the function entry point with a BRK, so
> that it can modify the LR _before_ it is saved to the stack. I don't see
> how SCS affects that.

You're correct. While this may not be optimal for reducing attack
surface, I just tested this to confirm that there's no functional
conflict. I'll drop this and related patches from v5.

Sami

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