3.18-stable review patch. If anyone has any objections, please let me know.
------------------ From: Tetsuo Handa <[email protected]> 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=3f86c0edf75c86d2633aeb9dd69eccc70bc7e90b Signed-off-by: Tetsuo Handa <[email protected]> Reported-by: syzbot <syzbot+9f03168400f56df89dbc6f1751f4458fe739f...@syzkaller.appspotmail.com> Reviewed-by: Greg Kroah-Hartman <[email protected]> Renamed sysfs_ready -> sysfs_inited. Signed-off-by: Jens Axboe <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- 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 @@ -803,16 +803,17 @@ 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 @@ -60,6 +60,7 @@ struct loop_device { wait_queue_head_t lo_event; /* wait queue for incoming requests */ wait_queue_head_t lo_req_wait; + bool sysfs_inited; struct request_queue *lo_queue; struct gendisk *lo_disk;
