linux-kernel - Re: [PATCH v1] Arm64: ASLR: fix text randomization

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Message-ID: <20141009144441.GA18384@leverpostej>
Date:	Thu, 9 Oct 2014 15:44:41 +0100
From:	Mark Rutland <mark.rutland@....com>
To:	Will Deacon <Will.Deacon@....com>
Cc:	Arun Chandran <achandran@...sta.com>,
	Catalin Marinas <Catalin.Marinas@....com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Anton Blanchard <anton@...ba.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Martin Schwidefsky <schwidefsky@...ibm.com>
Subject: Re: [PATCH v1] Arm64: ASLR: fix text randomization

On Wed, Oct 08, 2014 at 12:21:55PM +0100, Will Deacon wrote:
> On Wed, Oct 08, 2014 at 07:51:54AM +0100, Arun Chandran wrote:
> > On Tue, Oct 7, 2014 at 7:13 PM, Mark Rutland <mark.rutland@....com> wrote:
> > > I wasn't able to spot where the randomness came from in the
> > > ARCH_BINFMT_ELF_RANDOMIZE_PIE case, so it's not clear to me if the
> > > generic implementation behaves identically other than disabling
> > > randomization when told to via proc.
> > 
> > I also don't know from where it is coming; but it works on arm and x86 :)
> 
> The randomness will come from elf_map, since that will descend into the mmap
> code and end up with a randomised base address (see mmap_base and
> arch_pick_mmap_layout).

Given that, it sounds like the existing randomize_et_dyn is redundant?

If so, the patch looks sane to me.

Mark.
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