ksmbd: fix use-after-free in smb2_open during durable reconnect

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

ksmbd: fix use-after-free in smb2_open during durable reconnect

In smb2_open, the call to ksmbd_put_durable_fd(fp) drops the reference to the durable file descriptor early during the durable reconnect process. If an error occurs subsequently (eg, ksmbd_iov_pin_rsp fails) or a scavenger accesses the file, it leads to a use-after-free when accessing fp properties (eg fp->create_time).

Move the single put to the end of the function below err_out2 so fp stays valid until smb2_open returns.