[PATCH 1/2] thunderbolt: Validate DP bandwidth notification port

[Daehyeon Ko <4ncienth@gmail.com>]

The port number in a DP bandwidth notification is six bits wide and
comes from the router. A router whose maximum port number is smaller can
therefore make tb_handle_dp_bandwidth_request() index beyond the
max_port_number + 1 entries allocated for sw->ports. The first
tb_port_is_dpin() check then reads the out-of-bounds object.

Reject notifications that refer to a non-existent adapter before
dereferencing the port.

Fixes: 6ce3563520be ("thunderbolt: Add support for DisplayPort bandwidth allocation mode")
Cc: stable@vger.kernel.org
Assisted-by: LLM
Signed-off-by: Daehyeon Ko <4ncienth@gmail.com>
---
 drivers/thunderbolt/tb.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
index 47753a5c0f2eb..8551dafe98c8e 100644
--- a/drivers/thunderbolt/tb.c
+++ b/drivers/thunderbolt/tb.c
@@ -2756,6 +2756,11 @@ static void tb_handle_dp_bandwidth_request(struct work_struct *work)
 		goto unlock;
 	}
 
+	if (ev->port > sw->config.max_port_number) {
+		tb_sw_warn(sw, "bandwidth request from non-existent port %u\n",
+			   ev->port);
+		goto put_sw;
+	}
 	in = &sw->ports[ev->port];
 	if (!tb_port_is_dpin(in)) {
 		tb_port_warn(in, "bandwidth request to non-DP IN adapter\n");
-- 
2.55.0