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Date:   Thu, 21 Sep 2023 18:29:10 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Florent Revest <revest@chromium.org>
Cc:     linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        catalin.marinas@arm.com, anshuman.khandual@arm.com,
        joey.gouly@arm.com, mhocko@suse.com, keescook@chromium.org,
        david@redhat.com, peterx@redhat.com, izbyshev@ispras.ru,
        broonie@kernel.org, szabolcs.nagy@arm.com, kpsingh@kernel.org,
        gthelen@google.com, toiwoton@gmail.com, ayush.jain3@amd.com,
        stable@vger.kernel.org
Subject: Re: [PATCH v4 4/6] mm: Make PR_MDWE_REFUSE_EXEC_GAIN an unsigned
 long
Message-Id: <20230921182910.2fcce58b27b23f767050033c@linux-foundation.org>
In-Reply-To: <20230828150858.393570-5-revest@chromium.org>
References: <20230828150858.393570-1-revest@chromium.org>
        <20230828150858.393570-5-revest@chromium.org>
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On Mon, 28 Aug 2023 17:08:56 +0200 Florent Revest <revest@chromium.org> wrote:

> Defining a prctl flag as an int is a footgun because on a 64 bit machine
> and with a variadic implementation of prctl (like in musl and glibc),
> when used directly as a prctl argument, it can get casted to long with
> garbage upper bits which would result in unexpected behaviors.
> 
> This patch changes the constant to an unsigned long to eliminate that
> possibilities. This does not break UAPI.
> 
> Fixes: b507808ebce2 ("mm: implement memory-deny-write-execute as a prctl")
> Cc: stable@vger.kernel.org
> Signed-off-by: Florent Revest <revest@chromium.org>
> Suggested-by: Alexey Izbyshev <izbyshev@ispras.ru>
> Reviewed-by: David Hildenbrand <david@redhat.com>
> Reviewed-by: Kees Cook <keescook@chromium.org>
> Acked-by: Catalin Marinas <catalin.marinas@arm.com>

Why is this being offered to -stable?  Does it fix any known problem?