cifs: check kmalloc before use

cifs: check kmalloc before use

BugLink: https://bugs.launchpad.net/bugs/1835972
commit 126c97f4d0d1b5b956e8b0740c81a2b2a2ae548c upstream.

The kmalloc was not being checked - if it fails issue a warning
and return -ENOMEM to the caller.

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Fixes: b8da344b74c8 ("cifs: dynamic allocation of ntlmssp blob")
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
cc: Stable <stable@vger.kernel.org>`
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>