From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752404Ab2JGXVs (ORCPT ); Sun, 7 Oct 2012 19:21:48 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:38116 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752358Ab2JGXVp (ORCPT ); Sun, 7 Oct 2012 19:21:45 -0400 Message-Id: <20121007225835.149828981@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Sun, 07 Oct 2012 23:58:37 +0100 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Francesco Ruggeri , Linus Torvalds Subject: [ 003/108] fs/proc: fix potential unregister_sysctl_table hang In-Reply-To: <20121007225834.673681075@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:21c:bfff:fe03:f805 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Francesco Ruggeri commit 6bf6104573482570f7103d3e5ddf9574db43a363 upstream. The unregister_sysctl_table() function hangs if all references to its ctl_table_header structure are not dropped. This can happen sometimes because of a leak in proc_sys_lookup(): proc_sys_lookup() gets a reference to the table via lookup_entry(), but it does not release it when a subsequent call to sysctl_follow_link() fails. This patch fixes this leak by making sure the reference is always dropped on return. See also commit 076c3eed2c31 ("sysctl: Rewrite proc_sys_lookup introducing find_entry and lookup_entry") which reorganized this code in 3.4. Tested in Linux 3.4.4. Signed-off-by: Francesco Ruggeri Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings --- fs/proc/proc_sysctl.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c index dfafeb2..eb7cc91 100644 --- a/fs/proc/proc_sysctl.c +++ b/fs/proc/proc_sysctl.c @@ -462,9 +462,6 @@ static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry, err = ERR_PTR(-ENOMEM); inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p); - if (h) - sysctl_head_finish(h); - if (!inode) goto out; @@ -473,6 +470,8 @@ static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry, d_add(dentry, inode); out: + if (h) + sysctl_head_finish(h); sysctl_head_finish(head); return err; }