From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753418AbcAEU24 (ORCPT ); Tue, 5 Jan 2016 15:28:56 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:44969 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753194AbcAETrZ (ORCPT ); Tue, 5 Jan 2016 14:47:25 -0500 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Daniel Borkmann , Steven Rostedt , Kamal Mostafa Subject: [PATCH 4.2.y-ckt 086/211] tracefs: Fix refcount imbalance in start_creating() Date: Tue, 5 Jan 2016 11:43:14 -0800 Message-Id: <1452023119-25647-87-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1452023119-25647-1-git-send-email-kamal@canonical.com> References: <1452023119-25647-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 4.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.2.8-ckt1 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Daniel Borkmann commit d227c3ae4e94e5eb11dd780a811f59e1a7b74ccd upstream. In tracefs' 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 singleton 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. F.e., in securityfs_create_file(), after doing simple_pin_fs() when lookup_one_len() fails there, we infact do simple_release_fs(). This seems necessary here as well. Same issue seen in debugfs due to 190afd81e4a5 ("debugfs: split the beginning and the end of __create_file() off"), which seemed to got carried over into tracefs, too. Noticed during code review. Link: http://lkml.kernel.org/r/68efa86101b778cf7517ed7c6ad573bd69f60ec6.1446672850.git.daniel@iogearbox.net Fixes: 4282d60689d4 ("tracefs: Add new tracefs file system") Signed-off-by: Daniel Borkmann Signed-off-by: Steven Rostedt Signed-off-by: Kamal Mostafa --- fs/tracefs/inode.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c index cbc8d5d..c66f242 100644 --- a/fs/tracefs/inode.c +++ b/fs/tracefs/inode.c @@ -340,8 +340,12 @@ static struct dentry *start_creating(const char *name, struct dentry *parent) dput(dentry); dentry = ERR_PTR(-EEXIST); } - if (IS_ERR(dentry)) + + if (IS_ERR(dentry)) { mutex_unlock(&parent->d_inode->i_mutex); + simple_release_fs(&tracefs_mount, &tracefs_mount_count); + } + return dentry; } -- 1.9.1