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powerpc/iommu: Avoid derefence before pointer check

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[ Upstream commit 984ecdd68de0fa1f63ce205d6c19ef5a7bc67b40 ]

The tbl pointer is being derefenced by IOMMU_PAGE_SIZE prior the check
if it is not NULL.

Just moving the dereference code to after the check, where there will
be guarantee that 'tbl' will not be NULL.

Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Breno Leitao 2018-08-21 15:44:48 -03:00 committed by Greg Kroah-Hartman
parent 3b767de189
commit 6eb5dfdd45
1 changed files with 1 additions and 1 deletions
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2
arch/powerpc/kernel/iommu.c
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@ -764,9 +764,9 @@ dma_addr_t iommu_map_page(struct device *dev, struct iommu_table *tbl,
vaddr = page_address(page) + offset;
uaddr = (unsigned long)vaddr;
npages = iommu_num_pages(uaddr, size, IOMMU_PAGE_SIZE(tbl));
if (tbl) {
npages = iommu_num_pages(uaddr, size, IOMMU_PAGE_SIZE(tbl));
align = 0;
if (tbl->it_page_shift < PAGE_SHIFT && size >= PAGE_SIZE &&
((unsigned long)vaddr & ~PAGE_MASK) == 0)