Commit 381a3ce1 authored by Li Nan's avatar Li Nan Committed by Yu Kuai
Browse files

md: init bioset in mddev_init 

IO operations may be needed before md_run(), such as updating metadata
after writing sysfs. Without bioset, this triggers a NULL pointer
dereference as below:

 BUG: kernel NULL pointer dereference, address: 0000000000000020
 Call Trace:
  md_update_sb+0x658/0xe00
  new_level_store+0xc5/0x120
  md_attr_store+0xc9/0x1e0
  sysfs_kf_write+0x6f/0xa0
  kernfs_fop_write_iter+0x141/0x2a0
  vfs_write+0x1fc/0x5a0
  ksys_write+0x79/0x180
  __x64_sys_write+0x1d/0x30
  x64_sys_call+0x2818/0x2880
  do_syscall_64+0xa9/0x580
  entry_SYSCALL_64_after_hwframe+0x4b/0x53

Reproducer
```
  mdadm -CR /dev/md0 -l1 -n2 /dev/sd[cd]
  echo inactive > /sys/block/md0/md/array_state
  echo 10 > /sys/block/md0/md/new_level
```

mddev_init() can only be called once per mddev, no need to test if bioset
has been initialized anymore.

Link: https://lore.kernel.org/linux-raid/20251103125757.1405796-3-linan666@huaweicloud.com


Fixes: d981ed84 ("md: Add new_level sysfs interface")
Signed-off-by: default avatarLi Nan <linan122@huawei.com>
Reviewed-by: default avatarXiao Ni <xni@redhat.com>
Signed-off-by: default avatarYu Kuai <yukuai@fnnas.com>
parent 0ce112d9

drivers/md/md.c

+33 −36
Original line number Diff line number Diff line
@@ -730,6 +730,8 @@ static void mddev_clear_bitmap_ops(struct mddev *mddev) 


int mddev_init(struct mddev *mddev)

{

	int err = 0;



	if (!IS_ENABLED(CONFIG_MD_BITMAP))

		mddev->bitmap_id = ID_BITMAP_NONE;

	else
@@ -741,10 +743,23 @@ int mddev_init(struct mddev *mddev) 


	if (percpu_ref_init(&mddev->writes_pending, no_op,

			    PERCPU_REF_ALLOW_REINIT, GFP_KERNEL)) {

		percpu_ref_exit(&mddev->active_io);

		return -ENOMEM;

		err = -ENOMEM;

		goto exit_acitve_io;

	}



	err = bioset_init(&mddev->bio_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);

	if (err)

		goto exit_writes_pending;



	err = bioset_init(&mddev->sync_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);

	if (err)

		goto exit_bio_set;



	err = bioset_init(&mddev->io_clone_set, BIO_POOL_SIZE,

			  offsetof(struct md_io_clone, bio_clone), 0);

	if (err)

		goto exit_sync_set;



	/* We want to start with the refcount at zero */

	percpu_ref_put(&mddev->writes_pending);
@@ -773,11 +788,24 @@ int mddev_init(struct mddev *mddev) 
	INIT_WORK(&mddev->del_work, mddev_delayed_delete);



	return 0;



exit_sync_set:

	bioset_exit(&mddev->sync_set);

exit_bio_set:

	bioset_exit(&mddev->bio_set);

exit_writes_pending:

	percpu_ref_exit(&mddev->writes_pending);

exit_acitve_io:

	percpu_ref_exit(&mddev->active_io);

	return err;

}

EXPORT_SYMBOL_GPL(mddev_init);



void mddev_destroy(struct mddev *mddev)

{

	bioset_exit(&mddev->bio_set);

	bioset_exit(&mddev->sync_set);

	bioset_exit(&mddev->io_clone_set);

	percpu_ref_exit(&mddev->active_io);

	percpu_ref_exit(&mddev->writes_pending);

}
@@ -6394,29 +6422,9 @@ int md_run(struct mddev *mddev) 
		nowait = nowait && bdev_nowait(rdev->bdev);

	}



	if (!bioset_initialized(&mddev->bio_set)) {

		err = bioset_init(&mddev->bio_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);

		if (err)

			return err;

	}

	if (!bioset_initialized(&mddev->sync_set)) {

		err = bioset_init(&mddev->sync_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);

		if (err)

			goto exit_bio_set;

	}



	if (!bioset_initialized(&mddev->io_clone_set)) {

		err = bioset_init(&mddev->io_clone_set, BIO_POOL_SIZE,

				  offsetof(struct md_io_clone, bio_clone), 0);

		if (err)

			goto exit_sync_set;

	}



	pers = get_pers(mddev->level, mddev->clevel);

	if (!pers) {

		err = -EINVAL;

		goto abort;

	}

	if (!pers)

		return -EINVAL;

	if (mddev->level != pers->head.id) {

		mddev->level = pers->head.id;

		mddev->new_level = pers->head.id;
@@ -6427,8 +6435,7 @@ int md_run(struct mddev *mddev) 
	    pers->start_reshape == NULL) {

		/* This personality cannot handle reshaping... */

		put_pers(pers);

		err = -EINVAL;

		goto abort;

		return -EINVAL;

	}



	if (pers->sync_request) {
@@ -6555,12 +6562,6 @@ int md_run(struct mddev *mddev) 
	mddev->private = NULL;

	put_pers(pers);

	md_bitmap_destroy(mddev);

abort:

	bioset_exit(&mddev->io_clone_set);

exit_sync_set:

	bioset_exit(&mddev->sync_set);

exit_bio_set:

	bioset_exit(&mddev->bio_set);

	return err;

}

EXPORT_SYMBOL_GPL(md_run);
@@ -6785,10 +6786,6 @@ static void __md_stop(struct mddev *mddev) 
	mddev->private = NULL;

	put_pers(pers);

	clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);



	bioset_exit(&mddev->bio_set);

	bioset_exit(&mddev->sync_set);

	bioset_exit(&mddev->io_clone_set);

}



void md_stop(struct mddev *mddev)