From: Fenghua Yu <fenghua.yu@intel.com>
Date: Mon, 6 Apr 2009 18:21:49 +0000 (-0700)
Subject: Intel-IOMMU Alignment Issue in dma_pte_clear_range()
X-Git-Tag: v2.6.30-rc2~73^2~1
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=31d3568dfeb1dfb2735f119efe5ece7c6d40969c;p=pandora-kernel.git

Intel-IOMMU Alignment Issue in dma_pte_clear_range()

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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