On Fri 04-05-18 20:47:29, Tetsuo Handa wrote:
> >From 626d33de1b70b11ecaf95a9f83f7644998e54cbb Mon Sep 17 00:00:00 2001
> From: Tetsuo Handa <penguin-ker...@i-love.sakura.ne.jp>
> Date: Wed, 2 May 2018 23:03:48 +0900
> Subject: [PATCH] loop: remember whether sysfs_create_group() succeeded
>
> syzbot is hitting WARN() triggered by memory allocation fault
> injection [1] because loop module is calling sysfs_remove_group()
> when sysfs_create_group() failed.
> Fix this by remembering whether sysfs_create_group() succeeded.
>
> [1]
> https://syzkaller.appspot.com/bug?id=3f86c0edf75c86d2633aeb9dd69eccc70bc7e90b
>
> Signed-off-by: Tetsuo Handa <penguin-ker...@i-love.sakura.ne.jp>
> Reported-by: syzbot
> <syzbot+9f03168400f56df89dbc6f1751f4458fe739f...@syzkaller.appspotmail.com>
> Reviewed-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
> Cc: Jens Axboe <ax...@kernel.dk>
Looks good to me. You can add:
Reviewed-by: Jan Kara <j...@suse.cz>
Honza
> ---
> drivers/block/loop.c | 11 ++++++-----
> drivers/block/loop.h | 1 +
> 2 files changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> index 5d4e316..1d758d8 100644
> --- a/drivers/block/loop.c
> +++ b/drivers/block/loop.c
> @@ -809,16 +809,17 @@ static ssize_t loop_attr_dio_show(struct loop_device
> *lo, char *buf)
> .attrs= loop_attrs,
> };
>
> -static int loop_sysfs_init(struct loop_device *lo)
> +static void loop_sysfs_init(struct loop_device *lo)
> {
> - return sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj,
> - &loop_attribute_group);
> + lo->sysfs_ready = !sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj,
> + &loop_attribute_group);
> }
>
> static void loop_sysfs_exit(struct loop_device *lo)
> {
> - sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj,
> - &loop_attribute_group);
> + if (lo->sysfs_ready)
> + sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj,
> + &loop_attribute_group);
> }
>
> static void loop_config_discard(struct loop_device *lo)
> diff --git a/drivers/block/loop.h b/drivers/block/loop.h
> index b78de98..73c801f 100644
> --- a/drivers/block/loop.h
> +++ b/drivers/block/loop.h
> @@ -58,6 +58,7 @@ struct loop_device {
> struct kthread_worker worker;
> struct task_struct *worker_task;
> bool use_dio;
> + bool sysfs_ready;
>
> struct request_queue *lo_queue;
> struct blk_mq_tag_set tag_set;
> --
> 1.8.3.1
>
--
Jan Kara <j...@suse.com>
SUSE Labs, CR
