From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f200.google.com (mail-pf0-f200.google.com [209.85.192.200]) by kanga.kvack.org (Postfix) with ESMTP id D7E52828E5 for ; Fri, 17 Jun 2016 03:58:08 -0400 (EDT) Received: by mail-pf0-f200.google.com with SMTP id e189so147697869pfa.2 for ; Fri, 17 Jun 2016 00:58:08 -0700 (PDT) Received: from mail-pa0-x241.google.com (mail-pa0-x241.google.com. [2607:f8b0:400e:c03::241]) by mx.google.com with ESMTPS id f1si11067251pfb.251.2016.06.17.00.58.07 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 17 Jun 2016 00:58:07 -0700 (PDT) Received: by mail-pa0-x241.google.com with SMTP id hf6so5335278pac.2 for ; Fri, 17 Jun 2016 00:58:07 -0700 (PDT) From: js1304@gmail.com Subject: [PATCH v3 7/9] mm/page_owner: avoid null pointer dereference Date: Fri, 17 Jun 2016 16:57:37 +0900 Message-Id: <1466150259-27727-8-git-send-email-iamjoonsoo.kim@lge.com> In-Reply-To: <1466150259-27727-1-git-send-email-iamjoonsoo.kim@lge.com> References: <1466150259-27727-1-git-send-email-iamjoonsoo.kim@lge.com> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Vlastimil Babka , mgorman@techsingularity.net, Minchan Kim , Alexander Potapenko , Hugh Dickins , Michal Hocko , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Sasha Levin , Sudip Mukherjee , Sudip Mukherjee , Joonsoo Kim From: Sudip Mukherjee We have dereferenced page_ext before checking it. Lets check it first and then used it. Link: http://lkml.kernel.org/r/1465249059-7883-1-git-send-email-sudipm.mukherjee@gmail.com Signed-off-by: Sudip Mukherjee Signed-off-by: Joonsoo Kim --- mm/page_owner.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/mm/page_owner.c b/mm/page_owner.c index dc92241..ec6dc18 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -295,13 +295,15 @@ void __dump_page_owner(struct page *page) .skip = 0 }; depot_stack_handle_t handle; - gfp_t gfp_mask = page_ext->gfp_mask; - int mt = gfpflags_to_migratetype(gfp_mask); + gfp_t gfp_mask; + int mt; if (unlikely(!page_ext)) { pr_alert("There is not page extension available.\n"); return; } + gfp_mask = page_ext->gfp_mask; + mt = gfpflags_to_migratetype(gfp_mask); if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) { pr_alert("page_owner info is not active (free page?)\n"); -- 1.9.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org