From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:60554 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S969175AbdADUOU (ORCPT ); Wed, 4 Jan 2017 15:14:20 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mike Marshall , Martin Brandenburg , Nicolai Stange , Jaegeuk Kim Subject: [PATCH 4.9 48/83] f2fs: set ->owner for debugfs status files file_operations Date: Wed, 4 Jan 2017 21:06:40 +0100 Message-Id: <20170104200448.498830928@linuxfoundation.org> In-Reply-To: <20170104200446.541604386@linuxfoundation.org> References: <20170104200446.541604386@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Nicolai Stange commit 05e6ea2685c964db1e675a24a4f4e2adc22d2388 upstream. The struct file_operations instance serving the f2fs/status debugfs file lacks an initialization of its ->owner. This means that although that file might have been opened, the f2fs module can still get removed. Any further operation on that opened file, releasing included, will cause accesses to unmapped memory. Indeed, Mike Marshall reported the following: BUG: unable to handle kernel paging request at ffffffffa0307430 IP: [] full_proxy_release+0x24/0x90 <...> Call Trace: [] __fput+0xdf/0x1d0 [] ____fput+0xe/0x10 [] task_work_run+0x8e/0xc0 [] do_exit+0x2ae/0xae0 [] ? __audit_syscall_entry+0xae/0x100 [] ? syscall_trace_enter+0x1ca/0x310 [] do_group_exit+0x44/0xc0 [] SyS_exit_group+0x14/0x20 [] do_syscall_64+0x61/0x150 [] entry_SYSCALL64_slow_path+0x25/0x25 <...> ---[ end trace f22ae883fa3ea6b8 ]--- Fixing recursive fault but reboot is needed! Fix this by initializing the f2fs/status file_operations' ->owner with THIS_MODULE. This will allow debugfs to grab a reference to the f2fs module upon any open on that file, thus preventing it from getting removed. Fixes: 902829aa0b72 ("f2fs: move proc files to debugfs") Reported-by: Mike Marshall Reported-by: Martin Brandenburg Signed-off-by: Nicolai Stange Signed-off-by: Jaegeuk Kim Signed-off-by: Greg Kroah-Hartman --- fs/f2fs/debug.c | 1 + 1 file changed, 1 insertion(+) --- a/fs/f2fs/debug.c +++ b/fs/f2fs/debug.c @@ -373,6 +373,7 @@ static int stat_open(struct inode *inode } static const struct file_operations stat_fops = { + .owner = THIS_MODULE, .open = stat_open, .read = seq_read, .llseek = seq_lseek,