diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
index e680fcfdee609..758b988ac518a 100644
--- a/drivers/usb/typec/ucsi/ucsi.c
+++ b/drivers/usb/typec/ucsi/ucsi.c
@@ -216,14 +216,18 @@ void ucsi_altmode_update_active(struct ucsi_connector *con)
 					    con->partner_altmode[i] == altmode);
 }
 
-static u8 ucsi_altmode_next_mode(struct typec_altmode **alt, u16 svid)
+static int ucsi_altmode_next_mode(struct typec_altmode **alt, u16 svid)
 {
 	u8 mode = 1;
 	int i;
 
-	for (i = 0; alt[i]; i++)
+	for (i = 0; alt[i]; i++) {
+		if (i > MODE_DISCOVERY_MAX)
+			return -ERANGE;
+
 		if (alt[i]->svid == svid)
 			mode++;
+	}
 
 	return mode;
 }
@@ -258,8 +262,11 @@ static int ucsi_register_altmode(struct ucsi_connector *con,
 			goto err;
 		}
 
-		desc->mode = ucsi_altmode_next_mode(con->port_altmode,
-						    desc->svid);
+		ret = ucsi_altmode_next_mode(con->port_altmode, desc->svid);
+		if (ret < 0)
+			return ret;
+
+		desc->mode = ret;
 
 		switch (desc->svid) {
 		case USB_TYPEC_DP_SID:
@@ -292,8 +299,11 @@ static int ucsi_register_altmode(struct ucsi_connector *con,
 			goto err;
 		}
 
-		desc->mode = ucsi_altmode_next_mode(con->partner_altmode,
-						    desc->svid);
+		ret = ucsi_altmode_next_mode(con->partner_altmode, desc->svid);
+		if (ret < 0)
+			return ret;
+
+		desc->mode = ret;
 
 		alt = typec_partner_register_altmode(con->partner, desc);
 		if (IS_ERR(alt)) {