From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753709Ab3AGVXo (ORCPT ); Mon, 7 Jan 2013 16:23:44 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:38005 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751900Ab3AGVXn (ORCPT ); Mon, 7 Jan 2013 16:23:43 -0500 Date: Mon, 7 Jan 2013 13:23:41 -0800 From: Andrew Morton To: Lin Feng Cc: tj@kernel.org, mingo@kernel.org, yinghai@kernel.org, liwanp@linux.vnet.ibm.com, benh@kernel.crashing.org, tangchen@cn.fujitsu.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] mm: memblock: fix wrong memmove size in memblock_merge_regions() Message-Id: <20130107132341.c8ca0060.akpm@linux-foundation.org> In-Reply-To: <1357530096-28548-1-git-send-email-linfeng@cn.fujitsu.com> References: <1357530096-28548-1-git-send-email-linfeng@cn.fujitsu.com> X-Mailer: Sylpheed 3.0.2 (GTK+ 2.20.1; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 7 Jan 2013 11:41:36 +0800 Lin Feng wrote: > The memmove span covers from (next+1) to the end of the array, and the index > of next is (i+1), so the index of (next+1) is (i+2). So the size of remaining > array elements is (type->cnt - (i + 2)). What are the user-visible effects of this bug? > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -314,7 +314,8 @@ static void __init_memblock memblock_merge_regions(struct memblock_type *type) > } > > this->size += next->size; > - memmove(next, next + 1, (type->cnt - (i + 1)) * sizeof(*next)); > + /* move forward from next + 1, index of which is i + 2 */ > + memmove(next, next + 1, (type->cnt - (i + 2)) * sizeof(*next)); > type->cnt--; > } > } > -- > 1.7.11.7