Since this cred was not created with copy_creds(), it needs to get
initialized.  Otherwise use of syscall(__NR_keyctl, KEYCTL_SESSION_TO_PARENT);
can lead to a NULL deref.  Thanks to Robert for finding this.

But introduced by commit 47a150edc2a ("Cache user_ns in struct cred").

Signed-off-by: Serge E. Hallyn <[email protected]>
Reported-by: Robert Święcki <[email protected]>
Cc: David Howells <[email protected]>
Cc: [email protected] (2.6.39)
Signed-off-by: Linus Torvalds <[email protected]>