From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	Bryam Vargas <hexlabsecurity@proton.me>,
	Mika Westerberg <mika.westerberg@linux.intel.com>
Subject: [PATCH 5.10 386/389] thunderbolt: Bound the DROM dual link port number before indexing sw->ports
Date: Mon, 17 Aug 2026 15:33:45 +0200
Message-ID: <20260817132553.712241943@linuxfoundation.org>
In-Reply-To: <20260817132538.796021292@linuxfoundation.org>
References: <20260817132538.796021292@linuxfoundation.org>
User-Agent: quilt/0.69
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

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

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

From: Bryam Vargas <hexlabsecurity@proton.me>

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: stable@vger.kernel.org
Signed-off-by: Bryam Vargas <hexlabsecurity@proton.me>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/thunderbolt/eeprom.c |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

--- a/drivers/thunderbolt/eeprom.c
+++ b/drivers/thunderbolt/eeprom.c
@@ -367,9 +367,16 @@ 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;
 }