From: Breno Leitao Date: Tue, 21 Aug 2018 18:44:48 +0000 (-0300) Subject: powerpc/iommu: Avoid derefence before pointer check X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=984ecdd68de0fa1f63ce205d6c19ef5a7bc67b40;p=linux.git powerpc/iommu: Avoid derefence before pointer check 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 Signed-off-by: Michael Ellerman --- diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c index af7a20dc6e093..80b6caaa9b92e 100644 --- a/arch/powerpc/kernel/iommu.c +++ b/arch/powerpc/kernel/iommu.c @@ -785,9 +785,9 @@ 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)