From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_NEOMUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 671AEC46471 for ; Mon, 6 Aug 2018 10:22:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 139BE219CF for ; Mon, 6 Aug 2018 10:22:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 139BE219CF Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729718AbeHFMa2 (ORCPT ); Mon, 6 Aug 2018 08:30:28 -0400 Received: from mx2.suse.de ([195.135.220.15]:38312 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726901AbeHFMa2 (ORCPT ); Mon, 6 Aug 2018 08:30:28 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 755CBAECB; Mon, 6 Aug 2018 10:22:04 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id 9EFBC1E0501; Mon, 6 Aug 2018 12:22:03 +0200 (CEST) Date: Mon, 6 Aug 2018 12:22:03 +0200 From: Jan Kara To: Andrew Morton Cc: Jan Kara , Chengguang Xu , mgorman@techsingularity.net, jlayton@redhat.com, ak@linux.intel.com, mawilcox@microsoft.com, tim.c.chen@linux.intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Al Viro Subject: Re: [PATCH] mm: adjust max read count in generic_file_buffered_read() Message-ID: <20180806102203.hmobd26cujmlfcsw@quack2.suse.cz> References: <20180719081726.3341-1-cgxu519@gmx.com> <20180719085812.sjup2odrjyuigt3l@quack2.suse.cz> <20180720161429.d63dccb9f66799dc0ff74dba@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180720161429.d63dccb9f66799dc0ff74dba@linux-foundation.org> User-Agent: NeoMutt/20170912 (1.9.0) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 20-07-18 16:14:29, Andrew Morton wrote: > On Thu, 19 Jul 2018 10:58:12 +0200 Jan Kara wrote: > > > On Thu 19-07-18 16:17:26, Chengguang Xu wrote: > > > When we try to truncate read count in generic_file_buffered_read(), > > > should deliver (sb->s_maxbytes - offset) as maximum count not > > > sb->s_maxbytes itself. > > > > > > Signed-off-by: Chengguang Xu > > > > Looks good to me. You can add: > > > > Reviewed-by: Jan Kara > > Yup. > > What are the runtime effects of this bug? Good question. I think ->readpage() could be called for index beyond maximum file size supported by the filesystem leading to weird filesystem behavior due to overflows in internal calculations. Honza -- Jan Kara SUSE Labs, CR