From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753063Ab3LTXgt (ORCPT ); Fri, 20 Dec 2013 18:36:49 -0500 Received: from aserp1040.oracle.com ([141.146.126.69]:26029 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751039Ab3LTXgr (ORCPT ); Fri, 20 Dec 2013 18:36:47 -0500 Date: Fri, 20 Dec 2013 15:35:34 -0800 From: "Darrick J. Wong" To: Miklos Szeredi , Alexander Viro Cc: linux-kernel , linux-fsdevel , fuse-devel@lists.sourceforge.net, Richard Hansen Subject: [PATCH v2] fuse: Fix IOC_[GS]ET{FLAGS,VERSION} argument size brokenness. Message-ID: <20131220233534.GC10192@birch.djwong.org> References: <20131219232739.GA10192@birch.djwong.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131219232739.GA10192@birch.djwong.org> User-Agent: Mutt/1.5.21 (2010-09-15) X-Source-IP: acsinet21.oracle.com [141.146.126.237] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The IOC_[GS]ETFLAGS and IOC_[GS]ETVERSION ioctls, despite being defined to take a "long" parameter, actually take "int" parameters. FUSE unfortunately assumed that the ioctl definitions never lie, and transfers a long's worth of data in and out of userspace, which causes stack smashing in chattr, and other bugs elsewhere. So, special-case this in FUSE so that we don't crash userland. v2: Do the same for the IOC_[GS]ETVERSION ioctls, as Richard Hansen points out. Signed-off-by: Darrick J. Wong --- fs/fuse/file.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 7e70506..f8766ab 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -2385,6 +2385,22 @@ long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg, iov->iov_base = (void __user *)arg; iov->iov_len = _IOC_SIZE(cmd); + /* + * The IOC_[GS]ETFLAGS and IOC_[GS]ETVERSION ioctls take int + * parameters even though the ioctl definition specifies long. + * Userland has been expecting int for ages (and chattr + * segfaults on FUSE filesystems), so special case that here. + * The IOC32 variants were declared with int, so they don't + * need this correction. + */ + switch (cmd) { + case FS_IOC_GETFLAGS: + case FS_IOC_SETFLAGS: + case FS_IOC_GETVERSION: + case FS_IOC_SETVERSION: + iov->iov_len = sizeof(int); + } + if (_IOC_DIR(cmd) & _IOC_WRITE) { in_iov = iov; in_iovs = 1;