From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752305AbdDKMvN (ORCPT ); Tue, 11 Apr 2017 08:51:13 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:36197 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751951AbdDKMvL (ORCPT ); Tue, 11 Apr 2017 08:51:11 -0400 From: Colin King To: Andrew Morton , Vlastimil Babka , Minchan Kim , Mel Gorman , Johannes Weiner , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , "Kirill A . Shutemov" , linux-mm@kvack.org Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] mm/migrate: check for null vma before dereferencing it Date: Tue, 11 Apr 2017 13:51:02 +0100 Message-Id: <20170411125102.19497-1-colin.king@canonical.com> X-Mailer: git-send-email 2.11.0 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Colin Ian King check if vma is null before dereferencing it, this avoiding any potential null pointer dereferences on vma via the is_vm_hugetlb_page call or the direct vma->vm_flags reference. Detected with CoverityScan, CID#1427995 ("Dereference before null check") Signed-off-by: Colin Ian King --- mm/migrate.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/migrate.c b/mm/migrate.c index 7958dfa01b16..039f7bc3b9ee 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -2757,10 +2757,10 @@ int migrate_vma(const struct migrate_vma_ops *ops, /* Sanity check the arguments */ start &= PAGE_MASK; end &= PAGE_MASK; - if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL)) - return -EINVAL; if (!vma || !ops || !src || !dst || start >= end) return -EINVAL; + if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL)) + return -EINVAL; if (start < vma->vm_start || start >= vma->vm_end) return -EINVAL; if (end <= vma->vm_start || end > vma->vm_end) -- 2.11.0