Re: [PATCH v4 4/6] mm: Make PR_MDWE_REFUSE_EXEC_GAIN an unsigned long

[Andrew Morton]

On Mon, 28 Aug 2023 17:08:56 +0200 Florent Revest <revest@xxxxxxxxxxxx> 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@xxxxxxxxxxxxxxx
> Signed-off-by: Florent Revest <revest@xxxxxxxxxxxx>
> Suggested-by: Alexey Izbyshev <izbyshev@xxxxxxxxx>
> Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
> Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>

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