linux-kernel - Re: [PATCH] mm,ima,kexec: use memblock_free_late from ima_free_kexec

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Message-ID: <20230724233256.GA1124187-robh@kernel.org>
Date:   Mon, 24 Jul 2023 17:32:56 -0600
From:   Rob Herring <robh@...nel.org>
To:     Rik van Riel <riel@...riel.com>
Cc:     linux-kernel@...r.kernel.org, kernel-team@...a.com,
        Mike Rapoport <rppt@...nel.org>, devicetree@...r.kernel.org,
        x86@...nel.org, Juergen Gross <jgross@...e.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>
Subject: Re: [PATCH] mm,ima,kexec: use memblock_free_late from
 ima_free_kexec_buffer

On Fri, Jul 21, 2023 at 08:40:41PM -0400, Rik van Riel wrote:
> On Fri, 2023-07-21 at 13:38 -0600, Rob Herring wrote:
> > On Thu, Jul 20, 2023 at 10:14:31AM -0400, Rik van Riel wrote:
> > > The code calling ima_free_kexec_buffer runs long after the memblock
> > > allocator has already been torn down, potentially resulting in a
> > > use
> > > after free in memblock_isolate_range.
> > > 
> > > With KASAN or KFENCE, this use after free will result in a BUG
> > > from the idle task, and a subsequent kernel panic.
> > > 
> > > Switch ima_free_kexec_buffer over to memblock_free_late to avoid
> > > that issue.
> > > 
> > > Fixes: fee3ff99bc67 ("powerpc: Move arch independent ima kexec
> > > functions to drivers/of/kexec.c")
> > 
> > Fixes: b69a2afd5afc ("x86/kexec: Carry forward IMA measurement log on
> > kexec")
> > 
> Thank you for digging further back in the history of that code.
> 
> > Acked-by: Rob Herring <robh@...nel.org>
> > 
> > (I'm assuming someone else is taking this)
> 
> I hope so, but I don't know who...

You could split this into 2 patches, then there's no doubt. And each 
Fixes is clear.

Rob