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=-9.3 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 514F1C0650F for ; Mon, 5 Aug 2019 12:23:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 237F520856 for ; Mon, 5 Aug 2019 12:23:56 +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="NWW63Zur" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728779AbfHEMXy (ORCPT ); Mon, 5 Aug 2019 08:23:54 -0400 Received: from mail-pf1-f193.google.com ([209.85.210.193]:33427 "EHLO mail-pf1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727259AbfHEMXy (ORCPT ); Mon, 5 Aug 2019 08:23:54 -0400 Received: by mail-pf1-f193.google.com with SMTP id g2so39573414pfq.0 for ; Mon, 05 Aug 2019 05:23:54 -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=vlNVJGRhgAziAh7yL79j6BLAHuQYAgDj8JaIW0xteHA=; b=NWW63ZurGhueUM8XQrBDNSiWtLXfOiz6Mi9Q4GPGNJpL1wqX/27viVaEsBmqUIR8EC GYkilDyrrx1rQHS2QRsR1Z8IsLTeWpFlb1YDMFDmGcfnrvtt5cmQDMvYjBiTZ17TCUWS P8cst2qh/g9RWu4H/xuOSYkTT4IAn7LGt3vHT/U6usEDAMGWRf/2fKu7btfWpTi9P2Ro iz0/GQo+IpUahfCEqaokC0DMVUMZnDh0+7yH6oTQbeTkO3l158HEBbbzyLJSy+eA6/J1 xwoHb0+dP4iFZKiUR2xR8jBDBGAxTD8Ca1qjBKujoox2jaJJTx8fkpTw6jmkf9U2OSp/ N5Yw== 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=vlNVJGRhgAziAh7yL79j6BLAHuQYAgDj8JaIW0xteHA=; b=gwMnCy906cgigxHoKsmWRKVG1r+XjQF1m2aq/Y/SHahLLXckrikkujReFlJ5r1ZQAc p0aVVApb7oPiwEtkezbX7k+4HQd7q38vZn8VKjEWlmX6MUtWsXty8+LfXNLMv2048PqP KjuEBkikBBR7285Ljo2ikUgD/Z98nEYRr1i8QVrLdovOvG810KHwYCH+6zESRSiS4LA3 mHF9NPUO0JPvzN81XgiMKHQIN+/ltnAX0bOVGbhnmeGsX00ECSSeJpBrkXVJgojlrJhk u37x3blanDPk8gW0WfBQ+TeuHYiq0Y4Gkfd+f7wJ+ZQvlUE+6FHXH4zSCMPu50C0bjhh a6mA== X-Gm-Message-State: APjAAAUoUtBevLzgWCyr5jnsCv2xg3yQ2ma6g9HJZxWRQkNBIROlYIwa X/Ra4COJ2glLh5bTA4sEU7DACVPAsQKqpg== X-Google-Smtp-Source: APXvYqzZ5fX+/6jCq90JeFzTSdaNyhvmEKrGv8ZpMgNmYc3lp9VqctSVmhVbfapSDRkz0qpA8rwK8w== X-Received: by 2002:a63:ff20:: with SMTP id k32mr136655667pgi.445.1565007833544; Mon, 05 Aug 2019 05:23:53 -0700 (PDT) Received: from suzukaze.ipads-lab.se.sjtu.edu.cn ([89.31.126.54]) by smtp.gmail.com with ESMTPSA id j12sm75613114pff.4.2019.08.05.05.23.50 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Mon, 05 Aug 2019 05:23:52 -0700 (PDT) From: Chuhong Yuan Cc: linux-kernel@vger.kernel.org, Chuhong Yuan Subject: [PATCH v3 7/8] userns: Replace strncmp with str_has_prefix Date: Mon, 5 Aug 2019 20:23:46 +0800 Message-Id: <20190805122346.13203-1-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 to make code better. Signed-off-by: Chuhong Yuan --- Changes in v3: - Revise the description. 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