GetMemoryRegion() is used to obtain the attributes of an existing
mapping, to permit permission attribute changes to be optimized
away if the attributes don't actually change.
The current ARM code assumes that a section mapping or a page mapping
exists for any region passed into GetMemoryRegion(), but the region
may be unmapped entirely, in which case the code will crash. So check
if a section mapping exists before dereferencing it.
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
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