linux-kernel - Re: [PATCH 4.4 07/40] arm64: ensure __dump_instr() checks addr

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Date:   Mon, 20 Nov 2017 11:26:20 +0000
From:   Mark Rutland <mark.rutland@....com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Ben Hutchings <ben.hutchings@...ethink.co.uk>,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Will Deacon <will.deacon@....com>
Subject: Re: [PATCH 4.4 07/40] arm64: ensure __dump_instr() checks addr_limit

On Sun, Nov 19, 2017 at 11:29:35AM +0100, Greg Kroah-Hartman wrote:
> On Tue, Nov 14, 2017 at 04:18:23PM +0000, Mark Rutland wrote:
> > I agree that we need both patches. On its own (in the absence of PAN/UAO),
> > 57f4959bad0a154a wouldn't have any effect, but it is critical to ensure that we
> > can dump kernel instructions when we intend to, with 7a7003b1da010d2b
> > backported.
> > 
> > Backporting 57f4959bad0a154a as a prerequisite makes sense to me.
> 
> But that is a "new feature", are you sure about this?

Sorry, I copied the wrong commit ID when replying. I meant to say that
we should backport commit:

  c5cea06be060f38e ("arm64: fix dump_instr when PAN and UAO are in use")

... which on its own does nothing, but will prevent 7a7003b1da010d2b
from breaking kernel dumps.

We should *not* backport commit:

 57f4959bad0a154a ("arm64: kernel: Add support for User Access Override")

> So, just apply that one patch and we are all ok?  Nothing else?

Just apply c5cea06be060f38e as a prerequisite for 7a7003b1da010d2b, and
I think we're good. I'm not aware of anything else we need.

> confused,

Sorry about that. Hopefully the above clarified things?

Thanks,
Mark.