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=-9.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,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 91C84C76186 for ; Wed, 24 Jul 2019 02:22:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6411B20651 for ; Wed, 24 Jul 2019 02:22:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ny3XLJRQ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728467AbfGXCWu (ORCPT ); Tue, 23 Jul 2019 22:22:50 -0400 Received: from mail-pf1-f193.google.com ([209.85.210.193]:45305 "EHLO mail-pf1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726108AbfGXCWt (ORCPT ); Tue, 23 Jul 2019 22:22:49 -0400 Received: by mail-pf1-f193.google.com with SMTP id r1so20080564pfq.12 for ; Tue, 23 Jul 2019 19:22:49 -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; bh=zCkVmPbh59KCISPin/jSrbVrReqet2sJstHQ5eGtR7U=; b=ny3XLJRQPf+Dw89nJqn0yxwGVvyEo+yw4aHhY8LRHUveZBGnduMWeK0Ehv2ch0PjKQ Jb2P72uIbMz9NVBbwlhwqECG7b0REQ/mdjFEpyQJW073+Zvg1XvqPK2ePDQ5CR1I8NjS WW4L1d01yl/Oqdy65mhRYJCuCdb9vjMxFNtRmcowu6+iucEQz+ZYCnrrxygP1cwxx1x5 BBDIpCzGV/FuE4VhYPltQgUB10x00dierMso/k1yvpXtD4hVt33Xs+QBHc9tQTxkYNIq TddX0oHMwlbsie/++xpGkHkLXxlg0uvuLxF/Z8BsLjPuGefVILH3B6SZ2pj5eu8GrotT fx3w== 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; bh=zCkVmPbh59KCISPin/jSrbVrReqet2sJstHQ5eGtR7U=; b=sVJ6fhG165reMmD+IOwz6voRnXvqQqisaGBNXc/GGl9zGD+plblGgZJyxU0gVHPYUF Jaw6jJgxnxsG99xnH6zBhqBJ+v37vMF0bU9kl0BZX8csHaewqSB0oN47wjq8+TMhjRLk wD480p/NGqIoGosryfkewLRkrx+AHl3QLfFQ6/Myuklyd2cEU+sTAwtI26SPWjz1Le66 7M+4gf/JPxzGZRTAlyobxR05qx9Ge7e6gI3lQsJWpJvhzaOxTGGq5TyNTys/QGnv2dMo 3BoLINHOiYFHNPvr93qck+DlUe/uSEUEeo0vQ78tHrdx2dYttMgvrJr939jpehyjQaW+ hU/A== X-Gm-Message-State: APjAAAVLL18yQ13krOAZCcALKCePlwkjwiNfUqfY+xcYWrYKwV0E/Nfu +6hfLOB60g6Lc8BUiXLpzpF/sQ5g X-Google-Smtp-Source: APXvYqwDrVnSUej97+YGzUvpD6N7/FnuDIHjm9Djc3+tJpULk9Wo2hMToqGaWbdrLvn8dV6D0ckEtg== X-Received: by 2002:a63:484a:: with SMTP id x10mr21098240pgk.430.1563934969055; Tue, 23 Jul 2019 19:22:49 -0700 (PDT) Received: from oslab.tsinghua.edu.cn ([2402:f000:4:72:808::3ca]) by smtp.gmail.com with ESMTPSA id 137sm54994150pfz.112.2019.07.23.19.22.47 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 23 Jul 2019 19:22:48 -0700 (PDT) From: Jia-Ju Bai To: gregkh@linuxfoundation.org, tj@kernel.org Cc: linux-kernel@vger.kernel.org, Jia-Ju Bai Subject: [PATCH] fs: kernfs: Fix possible null-pointer dereferences in kernfs_path_from_node_locked() Date: Wed, 24 Jul 2019 10:22:42 +0800 Message-Id: <20190724022242.27505-1-baijiaju1990@gmail.com> X-Mailer: git-send-email 2.17.0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In kernfs_path_from_node_locked(), there is an if statement on line 147 to check whether buf is NULL: if (buf) When buf is NULL, it is used on line 151: len += strlcpy(buf + len, parent_str, ...) and line 158: len += strlcpy(buf + len, "/", ...) and line 160: len += strlcpy(buf + len, kn->name, ...) Thus, possible null-pointer dereferences may occur. To fix these possible bugs, buf is checked before being used. If it is NULL, -EINVAL is returned. These bugs are found by a static analysis tool STCheck written by us. Signed-off-by: Jia-Ju Bai --- fs/kernfs/dir.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index a387534c9577..9b01f6ce1d79 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -137,6 +137,9 @@ static int kernfs_path_from_node_locked(struct kernfs_node *kn_to, if (kn_from == kn_to) return strlcpy(buf, "/", buflen); + if (!buf) + return -EINVAL; + common = kernfs_common_ancestor(kn_from, kn_to); if (WARN_ON(!common)) return -EINVAL; @@ -144,8 +147,7 @@ static int kernfs_path_from_node_locked(struct kernfs_node *kn_to, depth_to = kernfs_depth(common, kn_to); depth_from = kernfs_depth(common, kn_from); - if (buf) - buf[0] = '\0'; + buf[0] = '\0'; for (i = 0; i < depth_from; i++) len += strlcpy(buf + len, parent_str, -- 2.17.0