CVE-2022-50672

In the Linux kernel, the following vulnerability has been resolved:

mailbox: zynq-ipi: fix error handling while device_register() fails

If deviceregister() fails, it has two issues: 1. The name allocated by devsetname() is leaked. 2. The parent of device is not NULL, deviceunregister() is called in zynqmpipifree_mboxes(), it will lead a kernel crash because of removing not added device.

Call putdevice() to give up the reference, so the name is freed in kobjectcleanup(). Add device registered check in zynqmpipifree_mboxes() to avoid null-ptr-deref.