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Commit adbbb863 authored by Miao Xie's avatar Miao Xie Committed by Chris Mason
Browse files

Btrfs: fix unprotected device list access when cloning fs devices 



We can build a new filesystem based a seed filesystem, and we need clone
the fs devices when we open the new filesystem. But someone might clear
the seed flag of the seed filesystem, then mount that filesystem and
remove some device. If we mount the new filesystem, we might access
a device list which was being changed when we clone the fs devices.
Fix it.

Signed-off-by: default avatarMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
parent 2196d6e8

fs/btrfs/volumes.c

+3 −0
Original line number Diff line number Diff line
@@ -583,6 +583,7 @@ static struct btrfs_fs_devices *clone_fs_devices(struct btrfs_fs_devices *orig) 
	if (IS_ERR(fs_devices))

		return fs_devices;



	mutex_lock(&orig->device_list_mutex);

	fs_devices->total_devices = orig->total_devices;



	/* We have held the volume lock, it is safe to get the devices. */
@@ -611,8 +612,10 @@ static struct btrfs_fs_devices *clone_fs_devices(struct btrfs_fs_devices *orig) 
		device->fs_devices = fs_devices;

		fs_devices->num_devices++;

	}

	mutex_unlock(&orig->device_list_mutex);

	return fs_devices;

error:

	mutex_unlock(&orig->device_list_mutex);

	free_fs_devices(fs_devices);

	return ERR_PTR(-ENOMEM);

}