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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 9B065C433B4 for ; Mon, 12 Apr 2021 03:03:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 65728610CB for ; Mon, 12 Apr 2021 03:03:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236603AbhDLDDK (ORCPT ); Sun, 11 Apr 2021 23:03:10 -0400 Received: from mail.loongson.cn ([114.242.206.163]:46202 "EHLO loongson.cn" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S235857AbhDLDDI (ORCPT ); Sun, 11 Apr 2021 23:03:08 -0400 Received: from [10.130.0.135] (unknown [113.200.148.30]) by mail.loongson.cn (Coremail) with SMTP id AQAAf9AxHck7uHNg698GAA--.9221S3; Mon, 12 Apr 2021 11:02:19 +0800 (CST) Subject: Re: [PATCH] MIPS: Fix strnlen_user access check To: Jinyang He , Thomas Bogendoerfer References: <1618139092-4018-1-git-send-email-hejinyang@loongson.cn> Cc: linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org From: Tiezhu Yang Message-ID: Date: Mon, 12 Apr 2021 11:02:19 +0800 User-Agent: Mozilla/5.0 (X11; Linux mips64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <1618139092-4018-1-git-send-email-hejinyang@loongson.cn> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CM-TRANSID: AQAAf9AxHck7uHNg698GAA--.9221S3 X-Coremail-Antispam: 1UD129KBjvJXoW7tw17XFWxCFWUAF4ktw1UKFg_yoW8WrW8pF s3Aw1kKFs0gryfAa4ay3y2qF1rGws8Gr1Y9a42gr1UZF1qvw15trWSkr1q93y8JFs8Aa4x WFWSqrn5Wr1jvw7anT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUvC14x267AKxVWUJVW8JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26F1j6w1UM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4U JVWxJr1l84ACjcxK6I8E87Iv67AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVCY1x0267AKxV WxJr0_GcWle2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2Wl Yx0E2Ix0cI8IcVAFwI0_JrI_JrylYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbV WUJVW8JwACjcxG0xvEwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1lc7I2V7IY0VAS07Al zVAYIcxG8wCY02Avz4vE14v_Gr4l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr 0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY 17CE14v26r126r1DMIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcV C0I7IYx2IY6xkF7I0E14v26r1j6r4UMIIF0xvE42xK8VAvwI8IcIk0rVWrZr1j6s0DMIIF 0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Jr0_GrUvcSsGvfC2Kf nxnUUI43ZEXa7VUjHGQDUUUUU== X-CM-SenderInfo: p1dqw3xlh2x3gn0dqz5rrqw2lrqou0/ Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/11/2021 07:04 PM, Jinyang He wrote: > Commit 04324f44cb69 ("MIPS: Remove get_fs/set_fs") brought a problem for > strnlen_user(). Jump out when checking access_ok() with condition that > (s + strlen(s)) < __UA_LIMIT <= (s + n). The old __strnlen_user_asm() > just checked (ua_limit & s) without checking (ua_limit & (s + n)). > Therefore, find strlen form s to __UA_LIMIT - 1 in that condition. > > Signed-off-by: Jinyang He > --- > arch/mips/include/asm/uaccess.h | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/arch/mips/include/asm/uaccess.h b/arch/mips/include/asm/uaccess.h > index 91bc7fb..85ba0c8 100644 > --- a/arch/mips/include/asm/uaccess.h > +++ b/arch/mips/include/asm/uaccess.h > @@ -630,8 +630,15 @@ static inline long strnlen_user(const char __user *s, long n) > { > long res; > > - if (!access_ok(s, n)) > - return -0; > + if (unlikely(n <= 0)) > + return 0; > + > + if (!access_ok(s, n)) { > + if (!access_ok(s, 0)) > + return 0; > + > + n = __UA_LIMIT - (unsigned long)s - 1; > + } > > might_fault(); > __asm__ __volatile__( The following simple changes are OK to fix this issue? diff --git a/arch/mips/include/asm/uaccess.h b/arch/mips/include/asm/uaccess.h index 91bc7fb..eafc99b 100644 --- a/arch/mips/include/asm/uaccess.h +++ b/arch/mips/include/asm/uaccess.h @@ -630,8 +630,8 @@ static inline long strnlen_user(const char __user *s, long n) { long res; - if (!access_ok(s, n)) - return -0; + if (!access_ok(s, 1)) + return 0; might_fault(); __asm__ __volatile__( Thanks, Tiezhu