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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 0BD12C432C0 for ; Fri, 22 Nov 2019 10:33:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D8BEF20708 for ; Fri, 22 Nov 2019 10:33:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574418805; bh=46tdXdSQHPeM2Uf2IhlUgJGdfheCHnVWs3MdbyS8Qd0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=dlFmossk6Yp8gKjIWJn2oLkt8yj2n53c6tOWJlVA19hDU8CNVZoRRSWhYau2S0jOi eLD/jye85HZhh5T8uv2ataqv9wSDos+jnzDA2NBLH2uRiOrHA0QbtWWY9oV6QAChtZ RY25WFPOt5uMIcO/GWZGThQ30/qPn2Q5QEqQe+nc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727933AbfKVKdY (ORCPT ); Fri, 22 Nov 2019 05:33:24 -0500 Received: from mail.kernel.org ([198.145.29.99]:55938 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727050AbfKVKdT (ORCPT ); Fri, 22 Nov 2019 05:33:19 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6983C20714; Fri, 22 Nov 2019 10:33:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574418798; bh=46tdXdSQHPeM2Uf2IhlUgJGdfheCHnVWs3MdbyS8Qd0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SGD66E1e/SrhG1HmwxmSXRxpK6t0p+wrpRc/2O9VuCEfxBMW57L+ABKIXH3CmOcdy 88UW1g2bzO+CnN3PO+38nOOY/uED3ltbHEWk3P05SFoaLliFUm2wxaCOaeIEW2yZCv cLOfOYOBhUJM9/U+BESvR8W0VzOcokgPis/QBD0Q= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Bernd Edlinger , Tejun Heo , Sasha Levin Subject: [PATCH 4.4 055/159] kernfs: Fix range checks in kernfs_get_target_path Date: Fri, 22 Nov 2019 11:27:26 +0100 Message-Id: <20191122100747.383847982@linuxfoundation.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191122100704.194776704@linuxfoundation.org> References: <20191122100704.194776704@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Bernd Edlinger [ Upstream commit a75e78f21f9ad4b810868c89dbbabcc3931591ca ] The terminating NUL byte is only there because the buffer is allocated with kzalloc(PAGE_SIZE, GFP_KERNEL), but since the range-check is off-by-one, and PAGE_SIZE==PATH_MAX, the returned string may not be zero-terminated if it is exactly PATH_MAX characters long. Furthermore also the initial loop may theoretically exceed PATH_MAX and cause a fault. Signed-off-by: Bernd Edlinger Acked-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- fs/kernfs/symlink.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/fs/kernfs/symlink.c b/fs/kernfs/symlink.c index b3b293e2c0990..0a379a86ff768 100644 --- a/fs/kernfs/symlink.c +++ b/fs/kernfs/symlink.c @@ -63,6 +63,9 @@ static int kernfs_get_target_path(struct kernfs_node *parent, if (base == kn) break; + if ((s - path) + 3 >= PATH_MAX) + return -ENAMETOOLONG; + strcpy(s, "../"); s += 3; base = base->parent; @@ -79,7 +82,7 @@ static int kernfs_get_target_path(struct kernfs_node *parent, if (len < 2) return -EINVAL; len--; - if ((s - path) + len > PATH_MAX) + if ((s - path) + len >= PATH_MAX) return -ENAMETOOLONG; /* reverse fillup of target string from target to base */ -- 2.20.1