From 43991e916eb9eac9ea0ef0317f9bfd3c491972cb Mon Sep 17 00:00:00 2001
From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Date: Fri, 4 May 2018 10:58:09 -0600
Subject: [PATCH] loop: remember whether sysfs_create_group() was done
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 <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(-)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index aaa7000a4342..da3902ac16c8 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -835,16 +835,17 @@ 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)
diff --git a/drivers/block/loop.h b/drivers/block/loop.h
index fb2237c73e61..60f0fd2c0c65 100644
--- 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;