linux-kernel - Re: [PATCH 09/11] x86: remove address space overrides using set

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Message-ID: <202008181246.A03BB9CEA@keescook>
Date:   Tue, 18 Aug 2020 12:46:41 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Christoph Hellwig <hch@....de>
Cc:     Al Viro <viro@...iv.linux.org.uk>,
        Michael Ellerman <mpe@...erman.id.au>, x86@...nel.org,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-arch@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH 09/11] x86: remove address space overrides using set_fs()

On Mon, Aug 17, 2020 at 09:32:10AM +0200, Christoph Hellwig wrote:
> Stop providing the possibility to override the address space using
> set_fs() now that there is no need for that any more.  To properly
> handle the TASK_SIZE_MAX checking for 4 vs 5-level page tables on
> x86 a new alternative is introduced, which just like the one in
> entry_64.S has to use the hardcoded virtual address bits to escape
> the fact that TASK_SIZE_MAX isn't actually a constant when 5-level
> page tables are enabled.
> 
> Signed-off-by: Christoph Hellwig <hch@....de>

Awesome. :)

Reviewed-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook