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 3931EFA372C for ; Fri, 8 Nov 2019 12:03:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0C5E221924 for ; Fri, 8 Nov 2019 12:03:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573214589; bh=ENGAVoNEsilAix5+Fhardf+5+hp2R8Zkomic5SD8fds=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=PV4o5rhzYF/Is1mNJcDCUyqwWf/nGUPW+PYExuitnBxdTuyL8RJbcEnIU5p5lNGLb jQCwH4/Ylzm0GbxznDWnlXWnhjNG99yVQ6H0Bx4oKQG4u0smkgXLY2GXra4m2ihSl0 0p7dXnus+h8AcH1rVppqsERrwIfjWZ61HIsqNyZg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391575AbfKHMDH (ORCPT ); Fri, 8 Nov 2019 07:03:07 -0500 Received: from mail.kernel.org ([198.145.29.99]:57066 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390189AbfKHLmu (ORCPT ); Fri, 8 Nov 2019 06:42:50 -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 65C9021D82; Fri, 8 Nov 2019 11:42:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573213370; bh=ENGAVoNEsilAix5+Fhardf+5+hp2R8Zkomic5SD8fds=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ABcoPQ0fN6QvqwqBC9r/G8ICnBk9YKiUs/FZdvFB1plmGmODT9YaCXCg3qTQGGUA/ /jvZ2mIsVN0I7sRJEbBCsP7g7rfo/PBYCKtSuAgQ2OPO32dxjqcOQAO5VOa1UAf+E/ +9FvhrOXTCceAdSJfHk3MXfWX76SFPLPeUvVHitU= 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 4.19 197/205] kernfs: Fix range checks in kernfs_get_target_path Date: Fri, 8 Nov 2019 06:37:44 -0500 Message-Id: <20191108113752.12502-197-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191108113752.12502-1-sashal@kernel.org> References: <20191108113752.12502-1-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 305b220af45d3..162f43b80c84c 100644 --- a/fs/kernfs/symlink.c +++ b/fs/kernfs/symlink.c @@ -72,6 +72,9 @@ 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; @@ -88,7 +91,7 @@ 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