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=-9.6 required=3.0 tests=DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 17FB5C433FF for ; Fri, 2 Aug 2019 01:47:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DE859206A3 for ; Fri, 2 Aug 2019 01:47:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="e2yaFF4R" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390638AbfHBBrp (ORCPT ); Thu, 1 Aug 2019 21:47:45 -0400 Received: from mail-pg1-f193.google.com ([209.85.215.193]:45545 "EHLO mail-pg1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727630AbfHBBrp (ORCPT ); Thu, 1 Aug 2019 21:47:45 -0400 Received: by mail-pg1-f193.google.com with SMTP id o13so35178134pgp.12 for ; Thu, 01 Aug 2019 18:47:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=iq2Oofr0Gl/QXG71RCvyorbUHlM5X2J3tGq+6DkFErQ=; b=e2yaFF4RWbkfUO1QTe/GDUHUpJSDfgDyYAIWk48MdUvp5QrvvaUQ6P/FVAQDGa+299 JOljzkOXkDdiCitVXPbnl+Ck0/SO4chaRleTHKKlGV8WVVCUn9aBOfk/i102nO37OrgF 278Xh/W+vjFHrksBgLaRfT302DmiCnZrW89qLs3Of2eMCG6H58gm7wo8xqT3XS309JH+ LBG7rfz8JPA9gkiRjfJC5Gy/UR3j4Gxc7h8m0UQbfwpfa477PBa4K1oWxStVlAZg5jWm bl5+a0DUnWxqzX+MrzFNxTCPCKvMS9snPerBRUyXrNx7yUG9JP3dR+GLNqlCoGY0gqd5 0CBg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=iq2Oofr0Gl/QXG71RCvyorbUHlM5X2J3tGq+6DkFErQ=; b=DCkm6/OZ7Yo7uKElXkxKUzyLJL/5rL4VTuJBiAmsRicSIsh2s46TdG1a+HbSPcpR2r zaIjeu23W+6QSFjGmLiBg3QZDMNocSjHriwqWPs5BWVyrrOH/pW3fItGsgYRcoMYe+eg y3/VAryEAkH3X7Sb6r0PymKYR0jcG6xflayTcNNBpsW8JzoVbu4wiH9Ko/39G8OpYsfI eQXjja+o6yrqJo5nbv+ySTY143Fq0AKbsF6PseZ9ZAJBDf+KxOfkoGuFOStVb75A95SL dcyGYny7H0QpxPs51fHlHQjTgnqE0a/HaXeA7HLdgmaQdsvf8Aa7t/LZyPpmeAziAq0R 3Scw== X-Gm-Message-State: APjAAAUUPsPM22WvmBYlOsvuJXhgxa2JM1tkJd37UoHF49O6eIQfM1wp fo7YdaEs2htCI33O+hQQCYksiZ8BIY2jfg== X-Google-Smtp-Source: APXvYqylsE993p8HGmSRYjY+kGu9oOVZpU+iKAj7W9WmiHyNUNaM2KM1gYLrbUtmFLBOzkTT6PIRtA== X-Received: by 2002:a62:6d84:: with SMTP id i126mr55568288pfc.129.1564710464729; Thu, 01 Aug 2019 18:47:44 -0700 (PDT) Received: from suzukaze.ipads-lab.se.sjtu.edu.cn ([89.31.126.54]) by smtp.gmail.com with ESMTPSA id w2sm63002010pgc.32.2019.08.01.18.47.42 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Thu, 01 Aug 2019 18:47:44 -0700 (PDT) From: Chuhong Yuan Cc: Greg Kroah-Hartman , linux-kernel@vger.kernel.org, Chuhong Yuan Subject: [PATCH v2 09/10] userns: Replace strncmp with str_has_prefix Date: Fri, 2 Aug 2019 09:47:39 +0800 Message-Id: <20190802014739.9114-1-hslester96@gmail.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit To: unlisted-recipients:; (no To-header on input) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org strncmp(str, const, len) is error-prone because len is easy to have typo. The example is the hard-coded len has counting error or sizeof(const) forgets - 1. So we prefer using newly introduced str_has_prefix to substitute such strncmp. Signed-off-by: Chuhong Yuan --- Changes in v2: - Revise the description. - Utilize str_has_prefix's return value to eliminate some hard codes. kernel/user_namespace.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c index 8eadadc478f9..e231e902df8a 100644 --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -1138,6 +1138,7 @@ ssize_t proc_setgroups_write(struct file *file, const char __user *buf, char kbuf[8], *pos; bool setgroups_allowed; ssize_t ret; + size_t len; /* Only allow a very narrow range of strings to be written */ ret = -EINVAL; @@ -1153,12 +1154,11 @@ ssize_t proc_setgroups_write(struct file *file, const char __user *buf, /* What is being requested? */ ret = -EINVAL; - if (strncmp(pos, "allow", 5) == 0) { - pos += 5; + if ((len = str_has_prefix(pos, "allow"))) { + pos += len; setgroups_allowed = true; - } - else if (strncmp(pos, "deny", 4) == 0) { - pos += 4; + } else if ((len = str_has_prefix(pos, "deny"))) { + pos += len; setgroups_allowed = false; } else -- 2.20.1