[PATCH 6.1 605/609] thunderbolt: Bound the DROM dual link port number before indexing sw->ports

6.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Bryam Vargas <[email protected]>

commit d6764992f17b23d91ff93ce905ab53c2aa7191f0 upstream.

tb_drom_parse_entry_port() validates the device-supplied header->index
against sw->config.max_port_number before indexing sw->ports[], but the
sibling field entry->dual_link_port_nr -- a 6-bit value also read from
the DROM -- indexes the same array with no such check. A malicious or
malformed Thunderbolt device can set dual_link_port_nr beyond the
allocated sw->ports[] (max_port_number + 1 entries), producing an
out-of-bounds tb_port pointer that is stored and later dereferenced.

Reject a port entry whose dual_link_port_nr exceeds max_port_number,
the same bound already applied to header->index.

Fixes: cd22e73bdf5e ("thunderbolt: Read port configuration from eeprom.")
Cc: [email protected]
Signed-off-by: Bryam Vargas <[email protected]>
Signed-off-by: Mika Westerberg <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 drivers/thunderbolt/eeprom.c |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

--- a/drivers/thunderbolt/eeprom.c
+++ b/drivers/thunderbolt/eeprom.c
@@ -392,9 +392,16 @@ static int tb_drom_parse_entry_port(stru
 			return -EIO;
 		}
 		port->link_nr = entry->link_nr;
-		if (entry->has_dual_link_port)
+		if (entry->has_dual_link_port) {
+			if (entry->dual_link_port_nr > sw->config.max_port_number) {
+				tb_sw_warn(sw,
+					"port entry has invalid dual link port number %u\n",
+					entry->dual_link_port_nr);
+				return -EIO;
+			}
 			port->dual_link_port =
 				&port->sw->ports[entry->dual_link_port_nr];
+		}
 	}
 	return 0;
 }