#define MBS_LINK_DOWN_ERROR            0x400B
 #define MBS_DIAG_ECHO_TEST_ERROR       0x400C
 
+static inline bool qla2xxx_is_valid_mbs(unsigned int mbs)
+{
+       return MBS_COMMAND_COMPLETE <= mbs && mbs <= MBS_DIAG_ECHO_TEST_ERROR;
+}
+
 /*
  * ISP mailbox asynchronous event status codes
  */
 
            fcport->fw_login_state, ea->rc, fcport->login_gen, ea->sp->gen2,
            fcport->rscn_gen, ea->sp->gen1, fcport->loop_id);
 
+       WARN_ONCE(!qla2xxx_is_valid_mbs(ea->data[0]), "mbs: %#x\n",
+                 ea->data[0]);
+
        if (ea->data[0] != MBS_COMMAND_COMPLETE) {
                ql_dbg(ql_dbg_disc, vha, 0x2066,
                    "%s %8phC: adisc fail: post delete\n",
 static void
 qla24xx_handle_prli_done_event(struct scsi_qla_host *vha, struct event_arg *ea)
 {
+       WARN_ONCE(!qla2xxx_is_valid_mbs(ea->data[0]), "mbs: %#x\n",
+                 ea->data[0]);
+
        switch (ea->data[0]) {
        case MBS_COMMAND_COMPLETE:
                ql_dbg(ql_dbg_disc, vha, 0x2118,
                return;
        }
 
+       WARN_ONCE(!qla2xxx_is_valid_mbs(ea->data[0]), "mbs: %#x\n",
+                 ea->data[0]);
+
        switch (ea->data[0]) {
        case MBS_COMMAND_COMPLETE:
                /*