From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f193.google.com ([209.85.192.193]:34495 "EHLO mail-pf0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751960AbdDNPkg (ORCPT ); Fri, 14 Apr 2017 11:40:36 -0400 Date: Sat, 15 Apr 2017 00:40:15 +0900 From: Minchan Kim To: Sergey Senozhatsky Cc: Andrew Morton , linux-kernel@vger.kernel.org, Sergey Senozhatsky , kernel-team@lge.com, stable@vger.kernel.org Subject: Re: [PATCH 2/3] zram: do not use copy_page with non-page alinged address Message-ID: <20170414154015.GB16910@bgram> References: <1492042622-12074-1-git-send-email-minchan@kernel.org> <1492042622-12074-2-git-send-email-minchan@kernel.org> <20170414054105.GC462@jagdpanzerIV.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170414054105.GC462@jagdpanzerIV.localdomain> Sender: stable-owner@vger.kernel.org List-ID: On Fri, Apr 14, 2017 at 02:41:05PM +0900, Sergey Senozhatsky wrote: > Hello, > > On (04/13/17 09:17), Minchan Kim wrote: > > The copy_page is optimized memcpy for page-alinged address. > > If it is used with non-page aligned address, it can corrupt memory which > > means system corruption. With zram, it can happen with > > > > 1. 64K architecture > > 2. partial IO > > 3. slub debug > > > > Partial IO need to allocate a page and zram allocates it via kmalloc. > > With slub debug, kmalloc(PAGE_SIZE) doesn't return page-size aligned > > address. And finally, copy_page(mem, cmem) corrupts memory. > > which would be the case for many other copy_page() calls in the kernel. > right? if so - should the fix be in copy_page() then? I thought about it but was not sure it's good idea by several reasons (but don't want to discuss it in this thread). Anyway, it's stable stuff so I don't want to make the patch bloat. If you believe it is right direction and valuable, you could be a volunteer. :) Thanks.