CIFS: fix use-after-free of the lease keys

CIFS: fix use-after-free of the lease keys

commit d339adc12a4f885b572c5412e4869af8939db854 upstream.

The request buffers are freed right before copying the pointers.
Use the func args instead which are identical and still valid.

Simple reproducer (requires KASAN enabled) on a cifs mount:

echo foo > foo ; tail -f foo & rm foo

Cc: <stable@vger.kernel.org> # 4.20
Fixes: 179e44d49c2f ("smb3: add tracepoint for sending lease break responses to server")
Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Paulo Alcantara <palcantara@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>