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loop: remember whether sysfs_create_group() was done 

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@I-love.SAKURA.ne.jp>
Reported-by: syzbot <syzbot+9f03168400f56df89dbc6f1751f4458fe739ff29@syzkaller.appspotmail.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Renamed sysfs_ready -> sysfs_inited.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Tetsuo Handa 2018-05-04 10:58:09 -06:00 committed by Jens Axboe
parent 50864670b3
commit d3349b6b3c
2 changed files with 7 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
drivers/block/loop.c
View File

@ -809,16 +809,17 @@ static struct attribute_group loop_attribute_group = {
.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_inited = !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_inited)
sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj,
&loop_attribute_group);
}
static void loop_config_discard(struct loop_device *lo)

1
drivers/block/loop.h
View File

@ -58,6 +58,7 @@ struct loop_device {
struct kthread_worker worker;
struct task_struct *worker_task;
bool use_dio;
bool sysfs_inited;
struct request_queue *lo_queue;
struct blk_mq_tag_set tag_set;