linux-kernel - Re: [PATCH V2] x86/ftrace: Make sure that ftrace trampolines are not RWX

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Date:   Thu, 25 May 2017 11:15:46 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Kees Cook <keescook@...omium.org>,
        LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Masami Hiramatsu <mhiramat@...nel.org>,
        "Luis R. Rodriguez" <mcgrof@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH V2] x86/ftrace: Make sure that ftrace trampolines are
 not RWX

On Thu, 25 May 2017 10:57:51 +0200 (CEST)
Thomas Gleixner <tglx@...utronix.de> wrote:

> ftrace use module_alloc() to allocate trampoline pages. The mapping of
> module_alloc() is RWX, which makes sense as the memory is written to
> right after allocation. But nothing makes these pages RO after
> writing to them.
> 
> Add proper set_memory_rw/ro() calls to protect the trampolines after
> modification.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

OK, I pulled this in and I'm currently running it through my test
suite. I'm about to board a flight, hopefully it runs smoothly and will
finish by the time I get home.

-- Steve