Describe CVE-2021-47307.
What is CVE-2021-47307?
In the Linux kernel, the following vulnerability has been resolved:

cifs: prevent NULL deref in cifs_compose_mount_options()

The optional @ref parameter might contain an NULL node_name, so
prevent dereferencing it in cifs_compose_mount_options().

Addresses-Coverity: 1476408 ("Explicit null dereferenced").