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=-3.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 465B8C56201 for ; Tue, 10 Nov 2020 19:18:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DD17C20829 for ; Tue, 10 Nov 2020 19:18:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="SXutxCxm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731527AbgKJTSo (ORCPT ); Tue, 10 Nov 2020 14:18:44 -0500 Received: from mail.kernel.org ([198.145.29.99]:56916 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726307AbgKJTSn (ORCPT ); Tue, 10 Nov 2020 14:18:43 -0500 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D3D512054F; Tue, 10 Nov 2020 19:18:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1605035923; bh=QyaQj8nTAcAePgBxv8GT7EUTzLqnjFIqlPDgD7W/gko=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=SXutxCxmOb4O7uW0nfSaG1esxskxJHgmpeYeSOOdlK9bujKeiUkijwgWvglSsfH0h 0UwJokCJsFTeHzDyS9tjtVxZEGXnYqzVLL2tQiOYsSse7EbDhsIVYigP4j4vK0GN2u 7zR074kr/3rwJbZkU/7M7V3lLz8Fw8aV1K2BKEj4= Date: Tue, 10 Nov 2020 11:18:42 -0800 From: Andrew Morton To: Yicong Yang Cc: , , , , , Subject: Re: [RESEND PATCH] libfs: fix error cast of negative value in simple_attr_write() Message-Id: <20201110111842.1bc76e9def94279d4453ff67@linux-foundation.org> In-Reply-To: <1605000324-7428-1-git-send-email-yangyicong@hisilicon.com> References: <1605000324-7428-1-git-send-email-yangyicong@hisilicon.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 10 Nov 2020 17:25:24 +0800 Yicong Yang wrote: > The attr->set() receive a value of u64, but simple_strtoll() is used > for doing the conversion. It will lead to the error cast if user inputs > a negative value. > > Use kstrtoull() instead of simple_strtoll() to convert a string got > from the user to an unsigned value. The former will return '-EINVAL' if > it gets a negetive value, but the latter can't handle the situation > correctly. > > ... > > --- a/fs/libfs.c > +++ b/fs/libfs.c > @@ -977,7 +977,9 @@ ssize_t simple_attr_write(struct file *file, const char __user *buf, > goto out; > > attr->set_buf[size] = '\0'; > - val = simple_strtoll(attr->set_buf, NULL, 0); > + ret = kstrtoull(attr->set_buf, 0, &val); > + if (ret) > + goto out; > ret = attr->set(attr->data, val); > if (ret == 0) > ret = len; /* on success, claim we got the whole input */ kstrtoull() takes an `unsigned long long *', but `val' is a u64. I think this probably works OK on all architectures (ie, no 64-bit architectures are using `unsigned long' for u64). But perhaps `val' should have type `unsigned long long'?