4.4-stable review patch. If anyone has any objections, please let me know.
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From: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp
commit d3349b6b3c373ac1fbfb040b810fcee5e2adc7e0 upstream.
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=3f86c0edf75c86d2633aeb9dd69eccc70bc7e90...
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/block/loop.c | 11 ++++++----- drivers/block/loop.h | 1 + 2 files changed, 7 insertions(+), 5 deletions(-)
--- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -835,16 +835,17 @@ static struct attribute_group loop_attri .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) --- a/drivers/block/loop.h +++ b/drivers/block/loop.h @@ -59,6 +59,7 @@ 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;