Vulnerability Advisory : Revert "kobject: Remove redundant checks for whether ktype is NULL" with undefined Attack Complexity

In the Linux kernel, the following vulnerability has been resolved: Revert "kobject: Remove redundant checks for whether ktype is NULL" This reverts commit 1b28cb81dab7c1eedc6034206f4e8d644046ad31. It is reported to cause problems, so revert it for now until the root cause can be found.