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Date: Fri, 10 May 2024 20:12:41 +0000
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Subject: [PATCH v5 1/4] usb: typec: ucsi: Fix null pointer dereference in trace
From: Jameson Thies <jthies@google.com>
To: heikki.krogerus@linux.intel.com, linux-usb@vger.kernel.org
Cc: jthies@google.com, pmalani@chromium.org, bleung@google.com, 
	abhishekpandit@chromium.org, andersson@kernel.org, 
	dmitry.baryshkov@linaro.org, fabrice.gasnier@foss.st.com, 
	gregkh@linuxfoundation.org, hdegoede@redhat.com, neil.armstrong@linaro.org, 
	rajaram.regupathy@intel.com, saranya.gopal@intel.com, 
	linux-kernel@vger.kernel.org, Benson Leung <bleung@chromium.org>
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From: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>

ucsi_register_altmode checks IS_ERR for the alt pointer and treats
NULL as valid. When CONFIG_TYPEC_DP_ALTMODE is not enabled,
ucsi_register_displayport returns NULL which causes a NULL pointer
dereference in trace. Rather than return NULL, call
typec_port_register_altmode to register DisplayPort alternate mode
as a non-controllable mode when CONFIG_TYPEC_DP_ALTMODE is not enabled.

Reviewed-by: Benson Leung <bleung@chromium.org>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Signed-off-by: Jameson Thies <jthies@google.com>
---
Changes in V5:
- Fixed signed off by line order.

Changes in V4:
- Updated commit message.

Changes in V3:
- Returns typec_port_register_altmode call from
ucsi_register_displayport when CONFIG_TYPEC_DP_ALTMODE is not enabled.
Updated commit message.

Changes in V2:
- Checks for error response from ucsi_register_displayport when
registering DisplayPort alternate mode.

 drivers/usb/typec/ucsi/ucsi.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/typec/ucsi/ucsi.h b/drivers/usb/typec/ucsi/ucsi.h
index c4d103db9d0f8..f66224a270bc6 100644
--- a/drivers/usb/typec/ucsi/ucsi.h
+++ b/drivers/usb/typec/ucsi/ucsi.h
@@ -496,7 +496,7 @@ ucsi_register_displayport(struct ucsi_connector *con,
 			  bool override, int offset,
 			  struct typec_altmode_desc *desc)
 {
-	return NULL;
+	return typec_port_register_altmode(con->port, desc);
 }
 
 static inline void
-- 
2.45.0.118.g7fe29c98d7-goog