From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:43496 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752826AbeAaQth (ORCPT ); Wed, 31 Jan 2018 11:49:37 -0500 Subject: Patch "loop: fix concurrent lo_open/lo_release" has been added to the 4.14-stable tree To: torvalds@linux-foundation.org, axboe@kernel.dk, ben.hutchings@codethink.co.uk, gregkh@linuxfoundation.org, long7573@126.com Cc: , From: Date: Wed, 31 Jan 2018 17:49:34 +0100 Message-ID: <1517417374496@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled loop: fix concurrent lo_open/lo_release to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: loop-fix-concurrent-lo_open-lo_release.patch and it can be found in the queue-4.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From ae6650163c66a7eff1acd6eb8b0f752dcfa8eba5 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Fri, 5 Jan 2018 16:26:00 -0800 Subject: loop: fix concurrent lo_open/lo_release MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Linus Torvalds commit ae6650163c66a7eff1acd6eb8b0f752dcfa8eba5 upstream. 范龙飞 reports that KASAN can report a use-after-free in __lock_acquire. The reason is due to insufficient serialization in lo_release(), which will continue to use the loop device even after it has decremented the lo_refcnt to zero. In the meantime, another process can come in, open the loop device again as it is being shut down. Confusion ensues. Reported-by: 范龙飞 Signed-off-by: Linus Torvalds Signed-off-by: Jens Axboe Cc: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- drivers/block/loop.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1576,9 +1576,8 @@ out: return err; } -static void lo_release(struct gendisk *disk, fmode_t mode) +static void __lo_release(struct loop_device *lo) { - struct loop_device *lo = disk->private_data; int err; if (atomic_dec_return(&lo->lo_refcnt)) @@ -1605,6 +1604,13 @@ static void lo_release(struct gendisk *d mutex_unlock(&lo->lo_ctl_mutex); } +static void lo_release(struct gendisk *disk, fmode_t mode) +{ + mutex_lock(&loop_index_mutex); + __lo_release(disk->private_data); + mutex_unlock(&loop_index_mutex); +} + static const struct block_device_operations lo_fops = { .owner = THIS_MODULE, .open = lo_open, Patches currently in stable-queue which might be from torvalds@linux-foundation.org are queue-4.14/futex-fix-owner_dead-fixup.patch queue-4.14/loop-fix-concurrent-lo_open-lo_release.patch