This issue was pointed out by Linus.
In dma_pte_clear_range() in intel-iommu.c
start = PAGE_ALIGN(start);
end &= PAGE_MASK;
npages = (end - start) / VTD_PAGE_SIZE;
In partial page case, start could be bigger than end and npages will be
negative.
Currently the issue doesn't show up as a real bug in because start and
end have been aligned to page boundary already by all callers. So the
issue has been hidden. But it is dangerous programming practice.
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
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