linux-kernel - Re: [PATCH v4 4/6] mm: Make PR_MDWE_REFUSE_EXEC

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Message-Id: <20230921182910.2fcce58b27b23f767050033c@linux-foundation.org>
Date:   Thu, 21 Sep 2023 18:29:10 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Florent Revest <revest@...omium.org>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        catalin.marinas@....com, anshuman.khandual@....com,
        joey.gouly@....com, mhocko@...e.com, keescook@...omium.org,
        david@...hat.com, peterx@...hat.com, izbyshev@...ras.ru,
        broonie@...nel.org, szabolcs.nagy@....com, kpsingh@...nel.org,
        gthelen@...gle.com, toiwoton@...il.com, ayush.jain3@....com,
        stable@...r.kernel.org
Subject: Re: [PATCH v4 4/6] mm: Make PR_MDWE_REFUSE_EXEC_GAIN an unsigned
 long

On Mon, 28 Aug 2023 17:08:56 +0200 Florent Revest <revest@...omium.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@...r.kernel.org
> Signed-off-by: Florent Revest <revest@...omium.org>
> Suggested-by: Alexey Izbyshev <izbyshev@...ras.ru>
> Reviewed-by: David Hildenbrand <david@...hat.com>
> Reviewed-by: Kees Cook <keescook@...omium.org>
> Acked-by: Catalin Marinas <catalin.marinas@....com>

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