linux-kernel - Re: [RESEND PATCH 0/2] Don't use SIGMINSTKSZ when enforcing alternative signal stack size for compat tasks

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Date:   Fri, 28 Sep 2018 14:18:11 +0100
From:   Steve McIntyre <93sam@...ian.org>
To:     Will Deacon <will.deacon@....com>
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        arnd@...db.de, linux@...inikbrodowski.net, ebiederm@...ssion.com,
        akpm@...ux-foundation.org, viro@...iv.linux.org.uk,
        oleg@...hat.com, dave.martin@....com
Subject: Re: [RESEND PATCH 0/2] Don't use SIGMINSTKSZ when enforcing
 alternative signal stack size for compat tasks

[ Re-sending without the corporate footer garbage... ]

On Wed, Sep 05, 2018 at 03:34:41PM +0100, Will Deacon wrote:
>Hi all,
>
>This is a resend of:
>
>  http://lists.infradead.org/pipermail/linux-arm-kernel/2018-July/593559.html
>
>now based on 4.19-rc2.
>
>The Debian folks have observed a failure in the 32-bit arm glibc testsuite
>when running under a 64-bit kernel. They tracked this down to sigaltstack(2)
>enforcing the alternative signal stack to be at least SIGMINSTKSZ bytes,
>which is higher for native arm64 tasks than compat 32-bit tasks.
>
>These patches resolve the issue by allowing an architecture to define
>COMPAT_SIGMINSTKSZ for compat tasks, which is then used by the sigaltstack
>checking code.
>
>Feedback welcome,

Apologies for the delayed response here - conference travel etc . got
in the way... I've just tested and I can confirm that this patchset
fixes our reported bug (as in https://bugs.debian.org/904385). Thanks
Will!

Tested-by: Steve McIntyre <93sam@...ian.org>

-- 
Steve McIntyre  <93sam@...ian.org>