diff --git a/drivers/thunderbolt/eeprom.c b/drivers/thunderbolt/eeprom.c
index 2a13fa6888ba..2acfe83928b6 100644
--- a/drivers/thunderbolt/eeprom.c
+++ b/drivers/thunderbolt/eeprom.c
@@ -324,7 +324,7 @@ int tb_drom_read_uid_only(struct tb_switch *sw, u64 *uid)
 }
 
 static int tb_drom_parse_entry_generic(struct tb_switch *sw,
-		struct tb_drom_entry_header *header)
+		const struct tb_drom_entry_header *header)
 {
 	const struct tb_drom_entry_generic *entry =
 		(const struct tb_drom_entry_generic *)header;
@@ -360,7 +360,7 @@ static int tb_drom_parse_entry_generic(struct tb_switch *sw,
 }
 
 static int tb_drom_parse_entry_port(struct tb_switch *sw,
-				    struct tb_drom_entry_header *header)
+				    const struct tb_drom_entry_header *header)
 {
 	struct tb_port *port;
 	int res;
@@ -386,11 +386,13 @@ static int tb_drom_parse_entry_port(struct tb_switch *sw,
 	type &= 0xffffff;
 
 	if (type == TB_TYPE_PORT) {
-		struct tb_drom_entry_port *entry = (void *) header;
+		const struct tb_drom_entry_port *entry =
+			(const struct tb_drom_entry_port *)header;
+
 		if (header->len != sizeof(*entry)) {
 			tb_sw_warn(sw,
 				"port entry has size %#x (expected %#zx)\n",
-				header->len, sizeof(struct tb_drom_entry_port));
+				header->len, sizeof(*entry));
 			return -EIO;
 		}
 		port->link_nr = entry->link_nr;
@@ -421,9 +423,16 @@ static int tb_drom_parse_entries(struct tb_switch *sw, size_t header_size)
 	int res;
 
 	while (pos < drom_size) {
-		struct tb_drom_entry_header *entry = (void *) (sw->drom + pos);
-		if (pos + 1 == drom_size || pos + entry->len > drom_size
-				|| !entry->len) {
+		const struct tb_drom_entry_header *entry;
+
+		if (drom_size - pos < sizeof(*entry)) {
+			tb_sw_warn(sw, "DROM buffer overrun\n");
+			return -EIO;
+		}
+
+		entry = (const struct tb_drom_entry_header *)(sw->drom + pos);
+		if (entry->len < sizeof(*entry) ||
+		    entry->len > drom_size - pos) {
 			tb_sw_warn(sw, "DROM buffer overrun\n");
 			return -EIO;
 		}