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=-9.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 E2375C56202 for ; Fri, 13 Nov 2020 12:35:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9C8E920797 for ; Fri, 13 Nov 2020 12:35:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726437AbgKMMfw (ORCPT ); Fri, 13 Nov 2020 07:35:52 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40816 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726160AbgKMMfv (ORCPT ); Fri, 13 Nov 2020 07:35:51 -0500 Received: from ZenIV.linux.org.uk (zeniv.linux.org.uk [IPv6:2002:c35c:fd02::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4C139C0613D1; Fri, 13 Nov 2020 04:35:51 -0800 (PST) Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kdYIm-0055Ez-9d; Fri, 13 Nov 2020 12:35:40 +0000 Date: Fri, 13 Nov 2020 12:35:40 +0000 From: Al Viro To: Yicong Yang Cc: akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org, akinobu.mita@gmail.com, linux-kernel@vger.kernel.org, linuxarm@huawei.com, prime.zeng@huawei.com Subject: Re: [PATCH v2] libfs: fix error cast of negative value in simple_attr_write() Message-ID: <20201113123540.GH3576660@ZenIV.linux.org.uk> References: <1605261369-551-1-git-send-email-yangyicong@hisilicon.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1605261369-551-1-git-send-email-yangyicong@hisilicon.com> Sender: Al Viro Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 13, 2020 at 05:56:09PM +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. > > Fixes: f7b88631a897 ("fs/libfs.c: fix simple_attr_write() on 32bit machines") > Signed-off-by: Yicong Yang > --- > Change since v1: > - address the compile warning for non-64 bit platform > > fs/libfs.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/fs/libfs.c b/fs/libfs.c > index fc34361..3a0d99c 100644 > --- 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, (unsigned long long *)&val); > + if (ret) > + goto out; > ret = attr->set(attr->data, val); > if (ret == 0) > ret = len; /* on success, claim we got the whole input */ Make val unsigned long long instead.