>From 626d33de1b70b11ecaf95a9f83f7644998e54cbb Mon Sep 17 00:00:00 2001 From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> 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-kernel@xxxxxxxxxxxxxxxxxxx> Reported-by: syzbot <syzbot+9f03168400f56df89dbc6f1751f4458fe739ff29@xxxxxxxxxxxxxxxxxxxxxxxxx> Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: Jens Axboe <axboe@xxxxxxxxx> --- 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
