From: Ard Biesheuvel <ardb@kernel.org>
To: Matthew Wilcox <willy@infradead.org>,
Kees Cook <keescook@chromium.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Cc: mail@horotw.com, linux-hardening@vger.kernel.org,
Jakub Wilk <jwilk@jwilk.net>,
Salvatore Bonaccorso <carnil@debian.org>,
Linux Memory Management List <linux-mm@kvack.org>,
William Kucharski <william.kucharski@oracle.com>
Subject: Re: Limited/Broken functionality of ASLR for Libs >= 2MB
Date: Tue, 16 Jan 2024 09:09:45 +0100 [thread overview]
Message-ID: <CAMj1kXGMPeFE_JAKBhAkh9eqmvEJjucsXru2bjc6oa35oyK4=A@mail.gmail.com> (raw)
In-Reply-To: <ZaWZqnD7XmP5HMA0@casper.infradead.org>
(cc Kees, LAKML)
https://lkml.kernel.org/r/69fa6015256613ed10aee996e181ebd4%40horotw.com
On Mon, 15 Jan 2024 at 21:46, Matthew Wilcox <willy@infradead.org> wrote:
>
...
> Yeah, I don't know either. Outside my scope of expertise.
>
> I received a suggestion off-list that we only do the PMD alignment on
> 64-bit, which seems quite reasonable to me. After all, I don't care
> about performance on 32-bit just as much as I don't care about security
> on 32-bit.
>
For context, the culprit is
commit 1854bc6e2420472676c5c90d3d6b15f6cd640e40
Author: William Kucharski <william.kucharski@oracle.com>
Date: Sun Sep 22 08:43:15 2019 -0400
mm/readahead: Align file mappings for non-DAX
When we have the opportunity to use PMDs to map a file, we want to follow
the same rules as DAX.
Signed-off-by: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
which affects *all* 32-bit architectures not just i686. 32-bit ARM
user space is still being deployed widely, even on arm64 Chromebooks
running 64-bit kernels (at least up until recently) so unfortunately,
we're not quite at the point yet where we can just let it rot.
next prev parent reply other threads:[~2024-01-16 8:10 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <69fa6015256613ed10aee996e181ebd4@horotw.com>
2024-01-15 16:40 ` Sam James
2024-01-15 16:52 ` Matthew Wilcox
2024-01-15 18:21 ` mail
2024-01-15 20:46 ` Matthew Wilcox
2024-01-16 8:09 ` Ard Biesheuvel [this message]
2024-01-23 22:35 ` Kees Cook
2024-01-24 1:04 ` Yang Shi
2024-01-24 16:08 ` Kees Cook
2024-01-22 9:48 ` Florian Weimer
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