From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752920AbdESOkt (ORCPT ); Fri, 19 May 2017 10:40:49 -0400 Received: from mail-pg0-f65.google.com ([74.125.83.65]:35122 "EHLO mail-pg0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750817AbdESOkr (ORCPT ); Fri, 19 May 2017 10:40:47 -0400 From: Firo Yang To: akpm@linux-foundation.org Cc: vbabka@suse.cz, mgorman@techsingularity.net, hannes@cmpxchg.org, mhocko@suse.com, bigeasy@linutronix.de, iamjoonsoo.kim@lge.com, rientjes@google.com, hughd@google.com, cl@linux.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Firo Yang Subject: [PATCH] mm, vmstat: Fix NULL pointer dereference during pagetypeinfo print Date: Fri, 19 May 2017 22:39:36 +0800 Message-Id: <20170519143936.21209-1-firogm@gmail.com> X-Mailer: git-send-email 2.9.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org During showing the pagetypeinfo, we forgot to save the found page and dereference a invalid page address from the stack. To fix it, save and reference the page address returned by pfn_to_online_page(). Signed-off-by: Firo Yang --- mm/vmstat.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/vmstat.c b/mm/vmstat.c index c432e58..6dae6b2 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -1223,7 +1223,8 @@ static void pagetypeinfo_showblockcount_print(struct seq_file *m, for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) { struct page *page; - if (!pfn_to_online_page(pfn)) + page = pfn_to_online_page(pfn); + if (!page) continue; /* Watch for unexpected holes punched in the memmap */ -- 2.9.4