cifs_check_receive(struct mid_q_entry *mid, struct TCP_Server_Info *server,
		   bool log_error)
{
	unsigned int len = get_rfc1002_length(mid->resp_buf) + 4;

	dump_smb(mid->resp_buf, min_t(u32, 92, len));

	/* convert the length into a more usable form */
	if (server->sec_mode & (SECMODE_SIGN_REQUIRED | SECMODE_SIGN_ENABLED)) {
		struct kvec iov;
		int rc = 0;
		struct smb_rqst rqst = { .rq_iov = &iov,
					 .rq_nvec = 1 };

		iov.iov_base = mid->resp_buf;
		iov.iov_len = len;
		/* FIXME: add code to kill session */
		rc = cifs_verify_signature(&rqst, server,
					   mid->sequence_number + 1);
		if (rc)
			cERROR(1, "SMB signature verification returned error = "
			       "%d", rc);
	}

	/* BB special case reconnect tid and uid here? */
	return map_smb_to_linux_error(mid->resp_buf, log_error);
}

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.