From: Anand Jain anand.jain@oracle.com
commit b5ddcffa37778244d5e786fe32f778edf2bfc93e upstream.
The following test case leads to NULL kobject free error:
mount seed /mnt add sprout to /mnt umount /mnt mount sprout to /mnt delete seed
kobject: '(null)' (00000000dd2b87e4): is not initialized, yet kobject_put() is being called. WARNING: CPU: 1 PID: 15784 at lib/kobject.c:736 kobject_put+0x80/0x350 RIP: 0010:kobject_put+0x80/0x350 :: Call Trace: btrfs_sysfs_remove_devices_dir+0x6e/0x160 [btrfs] btrfs_rm_device.cold+0xa8/0x298 [btrfs] btrfs_ioctl+0x206c/0x22a0 [btrfs] ksys_ioctl+0xe2/0x140 __x64_sys_ioctl+0x1e/0x29 do_syscall_64+0x96/0x150 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f4047c6288b ::
This is because, at the end of the seed device-delete, we try to remove the seed's devid sysfs entry. But for the seed devices under the sprout fs, we don't initialize the devid kobject yet. So add a kobject state check, which takes care of the bug.
Fixes: 668e48af7a94 ("btrfs: sysfs, add devid/dev_state kobject and device attributes") CC: stable@vger.kernel.org # 5.6+ Signed-off-by: Anand Jain anand.jain@oracle.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/btrfs/sysfs.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-)
--- a/fs/btrfs/sysfs.c +++ b/fs/btrfs/sysfs.c @@ -1165,10 +1165,12 @@ int btrfs_sysfs_remove_devices_dir(struc disk_kobj->name); }
- kobject_del(&one_device->devid_kobj); - kobject_put(&one_device->devid_kobj); + if (one_device->devid_kobj.state_initialized) { + kobject_del(&one_device->devid_kobj); + kobject_put(&one_device->devid_kobj);
- wait_for_completion(&one_device->kobj_unregister); + wait_for_completion(&one_device->kobj_unregister); + }
return 0; } @@ -1181,10 +1183,12 @@ int btrfs_sysfs_remove_devices_dir(struc sysfs_remove_link(fs_devices->devices_kobj, disk_kobj->name); } - kobject_del(&one_device->devid_kobj); - kobject_put(&one_device->devid_kobj); + if (one_device->devid_kobj.state_initialized) { + kobject_del(&one_device->devid_kobj); + kobject_put(&one_device->devid_kobj);
- wait_for_completion(&one_device->kobj_unregister); + wait_for_completion(&one_device->kobj_unregister); + } }
return 0;