From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 41w03F1YLTzF2FK for ; Wed, 22 Aug 2018 04:44:57 +1000 (AEST) Received: from pps.filterd (m0098399.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w7LIhtqD092627 for ; Tue, 21 Aug 2018 14:44:55 -0400 Received: from e12.ny.us.ibm.com (e12.ny.us.ibm.com [129.33.205.202]) by mx0a-001b2d01.pphosted.com with ESMTP id 2m0qw8rufn-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 21 Aug 2018 14:44:54 -0400 Received: from localhost by e12.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 21 Aug 2018 14:44:53 -0400 From: Breno Leitao To: linuxppc-dev@lists.ozlabs.org Cc: Alistair Popple , Breno Leitao Subject: [PATCH] powerpc/iommu: avoid derefence before pointer check Date: Tue, 21 Aug 2018 15:44:48 -0300 Message-Id: <1534877088-22303-1-git-send-email-leitao@debian.org> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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. CC: Alistair Popple Signed-off-by: Breno Leitao --- arch/powerpc/kernel/iommu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c index af7a20dc6e09..80b6caaa9b92 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) -- 2.16.3