From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757056AbdJKIxo (ORCPT ); Wed, 11 Oct 2017 04:53:44 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44870 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751415AbdJKIxm (ORCPT ); Wed, 11 Oct 2017 04:53:42 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 73CA4883C4 Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=shuwang@redhat.com From: shuwang@redhat.com To: catalin.marinas@arm.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, chuhu@redhat.com, yizhan@redhat.com, Shu Wang Subject: [PATCH] mm: kmemleak: start address align for scan_large_block Date: Wed, 11 Oct 2017 16:53:34 +0800 Message-Id: <20171011085334.7391-1-shuwang@redhat.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Wed, 11 Oct 2017 08:53:42 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Shu Wang If the start address is not ptr bytes aligned, it may cause false positives when a pointer is split by MAX_SCAN_SIZE. For example: tcp_metrics_nl_family is in __ro_after_init area. On my PC, the __start_ro_after_init is not ptr aligned, and tcp_metrics_nl_family->attrbuf was break by MAX_SCAN_SIZE. # cat /proc/kallsyms | grep __start_ro_after_init ffffffff81afac8b R __start_ro_after_init (gdb) p &tcp_metrics_nl_family->attrbuf (struct nlattr ***) 0xffffffff81b12c88 (gdb) p tcp_metrics_nl_family->attrbuf (struct nlattr **) 0xffff88007b9d9400 scan_block(_start=0xffffffff81b11c8b, _end=0xffffffff81b12c8b, 0) scan_block(_start=0xffffffff81b12c8b, _end=0xffffffff81b13c8b, 0) unreferenced object 0xffff88007b9d9400 (size 128): backtrace: kmemleak_alloc+0x4a/0xa0 __kmalloc+0xec/0x220 genl_register_family.part.8+0x11c/0x5c0 genl_register_family+0x6f/0x90 tcp_metrics_init+0x33/0x47 tcp_init+0x27a/0x293 inet_init+0x176/0x28a do_one_initcall+0x51/0x1b0 Signed-off-by: Shu Wang --- mm/kmemleak.c | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/kmemleak.c b/mm/kmemleak.c index 7780cd83a495..388b73e01fa4 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -1376,6 +1376,7 @@ static void scan_block(void *_start, void *_end, static void scan_large_block(void *start, void *end) { void *next; + start = PTR_ALIGN(start, BYTES_PER_POINTER); while (start < end) { next = min(start + MAX_SCAN_SIZE, end); -- 2.13.5