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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 766BFFA372C for ; Fri, 8 Nov 2019 11:47:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4013A222CE for ; Fri, 8 Nov 2019 11:47:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573213639; bh=dBhYL/8fBTCGaEmqO7RyJD8piCm0z71coejeJpx+Kp4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=PsFL6OnPjbffbyCjzXPKraXKdJoI9kVu/hcWVvOfUpSR54o5/1XaEhFU+qXGE/2mN fwmGLi6UbDsXRKz4KnxBZsxw81jJt55oIJXKg0IkBJ00xSQy6oGzDzyOF8xLDZASTy 9HbgSphzg26pNR39qYOCz+WruvDPirvW4IQ2+RSM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391529AbfKHLrR (ORCPT ); Fri, 8 Nov 2019 06:47:17 -0500 Received: from mail.kernel.org ([198.145.29.99]:35614 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391512AbfKHLrO (ORCPT ); Fri, 8 Nov 2019 06:47:14 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A78F32245A; Fri, 8 Nov 2019 11:47:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573213634; bh=dBhYL/8fBTCGaEmqO7RyJD8piCm0z71coejeJpx+Kp4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PGhI5DcKIVqKZBJrHuER7PTTfuTSmgFd9mrMGYyxk/+C9jRYxkme3nP1QwQjYl2Y5 iKGqkGxv4eyb2en9eq5LwcGWxaJ6aTuXE3U/8ZE1C448jc40RY0rZrcXUkTqINiWQ0 lRpJoak3A/YO9z00YOEsYwO58vD+DSGBA+tIYzmA= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Bernd Edlinger , Tejun Heo , Greg Kroah-Hartman , Sasha Levin Subject: [PATCH AUTOSEL 4.9 61/64] kernfs: Fix range checks in kernfs_get_target_path Date: Fri, 8 Nov 2019 06:45:42 -0500 Message-Id: <20191108114545.15351-61-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191108114545.15351-1-sashal@kernel.org> References: <20191108114545.15351-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore 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 80317b04c84a2..e431a850f2f2b 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