From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Daniel Borkmann , Al Viro Subject: [PATCH 4.3 62/71] debugfs: fix refcount imbalance in start_creating Date: Sat, 12 Dec 2015 12:06:26 -0800 Message-Id: <20151212200539.783369500@linuxfoundation.org> In-Reply-To: <20151212200536.761001328@linuxfoundation.org> References: <20151212200536.761001328@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Daniel Borkmann commit 0ee9608c89e81a1ccee52ecb58a7ff040e2522d9 upstream. In debugfs' start_creating(), we pin the file system to safely access its root. When we failed to create a file, we unpin the file system via failed_creating() to release the mount count and eventually the reference of the vfsmount. However, when we run into an error during lookup_one_len() when still in start_creating(), we only release the parent's mutex but not so the reference on the mount. Looks like it was done in the past, but after splitting portions of __create_file() into start_creating() and end_creating() via 190afd81e4a5 ("debugfs: split the beginning and the end of __create_file() off"), this seemed missed. Noticed during code review. Fixes: 190afd81e4a5 ("debugfs: split the beginning and the end of __create_file() off") Signed-off-by: Daniel Borkmann Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman --- fs/debugfs/inode.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) --- a/fs/debugfs/inode.c +++ b/fs/debugfs/inode.c @@ -271,8 +271,12 @@ static struct dentry *start_creating(con dput(dentry); dentry = ERR_PTR(-EEXIST); } - if (IS_ERR(dentry)) + + if (IS_ERR(dentry)) { mutex_unlock(&d_inode(parent)->i_mutex); + simple_release_fs(&debugfs_mount, &debugfs_mount_count); + } + return dentry; }