On Fri 04-05-18 20:47:29, Tetsuo Handa wrote: > >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> Looks good to me. You can add: Reviewed-by: Jan Kara <jack@xxxxxxx> 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 <jack@xxxxxxxx> SUSE Labs, CR
