Return-Path: Received: from mail.kernel.org ([198.145.29.99]:59176 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727332AbeLKPmq (ORCPT ); Tue, 11 Dec 2018 10:42:46 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Pan Bian , Jan Kara Subject: [PATCH 3.18 08/54] ext2: fix potential use after free Date: Tue, 11 Dec 2018 16:40:56 +0100 Message-Id: <20181211151546.448597786@linuxfoundation.org> In-Reply-To: <20181211151546.010073210@linuxfoundation.org> References: <20181211151546.010073210@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Pan Bian commit ecebf55d27a11538ea84aee0be643dd953f830d5 upstream. The function ext2_xattr_set calls brelse(bh) to drop the reference count of bh. After that, bh may be freed. However, following brelse(bh), it reads bh->b_data via macro HDR(bh). This may result in a use-after-free bug. This patch moves brelse(bh) after reading field. CC: stable@vger.kernel.org Signed-off-by: Pan Bian Signed-off-by: Jan Kara Signed-off-by: Greg Kroah-Hartman --- fs/ext2/xattr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/ext2/xattr.c +++ b/fs/ext2/xattr.c @@ -606,9 +606,9 @@ skip_replace: } cleanup: - brelse(bh); if (!(bh && header == HDR(bh))) kfree(header); + brelse(bh); up_write(&EXT2_I(inode)->xattr_sem); return error;