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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 77206C00319 for ; Tue, 5 Mar 2019 04:26:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3DA4D2075B for ; Tue, 5 Mar 2019 04:26:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="XXDwgpRQ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726965AbfCEE0d (ORCPT ); Mon, 4 Mar 2019 23:26:33 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:34656 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726522AbfCEE0c (ORCPT ); Mon, 4 Mar 2019 23:26:32 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=JwwcttM2cWT4KB8XyzeEqi7PlaKzpJpbAYIc//MbWhM=; b=XXDwgpRQQ2gcdgdzAsUszn0GB +F8s10psmzKqTr1ZWB59rBYnUQkANcv6WiNEM5n6F+kYoUrK2XSbKFLU/gwP6/psFBVD4odJGgeGt Qg1wOxnIaZOR7dmewYd6g/+0XFpNswRdYmX0G2KuXgZc0vNvOV65CEwewPxr6tqR0hpENVNMX9AE5 k1bzuUkElKrqOl9ZVggvcsr1/oQL48x+WRQGU0+BEezMFPHLOEGBH6TlVE9/8w/O4/AMWWAh7rp/n wf2LeDqMf5QN+BQULMoySGdpMkTL+VfhNnD1W7IQYfbGOTCzMD2ZzvgTrajofP72b2mHtPZT3V9Ov qJQ15CRPQ==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1h11er-0002Qv-FN; Tue, 05 Mar 2019 04:26:25 +0000 Date: Mon, 4 Mar 2019 20:26:25 -0800 From: Matthew Wilcox To: Hongbo Yao Cc: viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linuxarm@huawei.com Subject: Re: [PATCH] fs: Avoid signed overflow UBSAN warning Message-ID: <20190305042625.GC13380@bombadil.infradead.org> References: <20190223090210.116847-1-yaohongbo@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190223090210.116847-1-yaohongbo@huawei.com> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Sat, Feb 23, 2019 at 05:02:10PM +0800, Hongbo Yao wrote: > I ran into this: > UBSAN: Undefined behaviour in fs/read_write.c:251:11 > signed integer overflow: > 9223372036854775805 + 9223372036854775805 cannot be represented in > type 'long long int' > > Use unsigned types to do math, it doesn't throw a UBSAN warning > when it does overflow.This patch doesn't change generated code. You don't need to be this verbose to fix it. > - offset += file->f_pos; > + offset = (u64)file->f_pos + (u64)offset; offset += (u64)file->f_pos;