From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lb0-f199.google.com (mail-lb0-f199.google.com [209.85.217.199]) by kanga.kvack.org (Postfix) with ESMTP id 302036B007E for ; Mon, 6 Jun 2016 17:37:47 -0400 (EDT) Received: by mail-lb0-f199.google.com with SMTP id jf8so35144917lbc.3 for ; Mon, 06 Jun 2016 14:37:47 -0700 (PDT) Received: from mail-wm0-x242.google.com (mail-wm0-x242.google.com. [2a00:1450:400c:c09::242]) by mx.google.com with ESMTPS id e17si7591500wjx.37.2016.06.06.14.37.45 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 06 Jun 2016 14:37:46 -0700 (PDT) Received: by mail-wm0-x242.google.com with SMTP id n184so19613964wmn.1 for ; Mon, 06 Jun 2016 14:37:45 -0700 (PDT) From: Sudip Mukherjee Subject: [PATCH] mm/page_owner: avoid null pointer dereference Date: Mon, 6 Jun 2016 22:37:39 +0100 Message-Id: <1465249059-7883-1-git-send-email-sudipm.mukherjee@gmail.com> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Sudip Mukherjee We have dereferenced page_ext before checking it. Lets check it first and then used it. Signed-off-by: Sudip Mukherjee --- 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 587dcca..8fa5083 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -291,13 +291,15 @@ 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