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Re: [PATCH 1/3] xen/arm: Fix off-by-one in iomem_deny_access() calls
- To: Luca Fancellu <Luca.Fancellu@xxxxxxx>
- From: Stefano Stabellini <stefano.stabellini@xxxxxxx>
- Date: Thu, 9 Apr 2026 17:03:11 -0700
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- Cc: Michal Orzel <michal.orzel@xxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Bertrand Marquis <Bertrand.Marquis@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
- Delivery-date: Fri, 10 Apr 2026 00:03:44 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On Thu, 9 Apr 2026, Luca Fancellu wrote:
> Hi Michal,
>
> > On 9 Apr 2026, at 12:39, Michal Orzel <michal.orzel@xxxxxxx> wrote:
> >
> > iomem_deny_access() wraps rangeset_remove_range() which takes inclusive
> > endpoints. All call sites in the GIC and ACPI code pass 'mfn + nr' (or
> > 'mfn + 1' for single-page regions) as the end parameter, which causes
> > one extra page beyond each region to be denied.
> >
> > For single-page regions, use 'mfn' as the end (denying exactly one page).
> > For all multi-page regions, use 'mfn + nr - 1'.
> >
> > This matches the correct pattern used elsewhere, e.g. in device.c.
> >
> > Fixes: 8300b3377e ("arm/gic: Add a new callback to deny Dom0 access to GIC
> > regions")
> > Fixes: 66158be465 ("ARM: ITS: Deny hardware domain access to ITS")
> > Fixes: 97e9875646 ("arm/acpi: Permit MMIO access of Xen unused devices for
> > Dom0")
> > Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx>
> > ---
> >
>
> This looks ok to me.
>
> Reviewed-by: Luca Fancellu <luca.fancellu@xxxxxxx>
Reviewed-by: Stefano Stabellini <stefano.stabellini@xxxxxxx>
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