linux-kernel - [PATCH] usb: typec: Only attempt to link USB ports if there is fwnode

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Date:   Tue, 18 Jan 2022 12:36:27 +0300
From:   Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Robert Święcki <robert@...ecki.net>,
        Mikhail Gavrilov <mikhail.v.gavrilov@...il.com>
Subject: [PATCH] usb: typec: Only attempt to link USB ports if there is fwnode

The code that creates the links to the USB ports attached to
a connector inside the system assumed that the ACPI nodes
(fwnodes) always exist for the connectors, but it can not do
that.

There is no guarantee that every USB Type-C connector has
ACPI device node representing it in the ACPI tables, and
even if there are the nodes in the ACPI tables, the _STA
method in those nodes may still return 0 (which means the
device does not exist from ACPI PoW).

This fixes NULL pointer dereference that happens if the
nodes are missing.

Reported-and-tested-by: Robert Święcki <robert@...ecki.net>
Reported-by: Mikhail Gavrilov <mikhail.v.gavrilov@...il.com>
Fixes: 730b49aac426 ("usb: typec: port-mapper: Convert to the component framework")
Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
---
Hi guys,

Mikhail, I got confirmation from Robert that the patch fixes the
issue.

thanks,
---
 drivers/usb/typec/port-mapper.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/typec/port-mapper.c b/drivers/usb/typec/port-mapper.c
index 07d307418b470..b6e0c6acc628c 100644
--- a/drivers/usb/typec/port-mapper.c
+++ b/drivers/usb/typec/port-mapper.c
@@ -56,6 +56,9 @@ int typec_link_ports(struct typec_port *con)
 {
 	struct each_port_arg arg = { .port = con, .match = NULL };
 
+	if (!has_acpi_companion(&con->dev))
+		return 0;
+
 	bus_for_each_dev(&acpi_bus_type, NULL, &arg, typec_port_match);
 
 	/*
@@ -74,5 +77,6 @@ int typec_link_ports(struct typec_port *con)
 
 void typec_unlink_ports(struct typec_port *con)
 {
-	component_master_del(&con->dev, &typec_aggregate_ops);
+	if (has_acpi_companion(&con->dev))
+		component_master_del(&con->dev, &typec_aggregate_ops);
 }
-- 
2.34.1