usb: typec: ucsi: displayport: Fix a potential race during registration

Locking the connector in ucsi_register_displayport() to make
sure that nothing can access the displayport alternate mode
before the function has finished and the alternate mode is
actually ready.

Fixes: af8622f6a585 ("usb: typec: ucsi: Support for DisplayPort alt mode")
Cc: stable@vger.kernel.org
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20200311130006.41288-3-heikki.krogerus@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/typec/ucsi/displayport.c b/drivers/usb/typec/ucsi/displayport.c
index 261131c..048381c 100644 (file)
--- a/drivers/usb/typec/ucsi/displayport.c
+++ b/drivers/usb/typec/ucsi/displayport.c
@@ -288,6 +288,8 @@ struct typec_altmode *ucsi_register_displayport(struct ucsi_connector *con,
        struct typec_altmode *alt;
        struct ucsi_dp *dp;
 
+       mutex_lock(&con->lock);
+
        /* We can't rely on the firmware with the capabilities. */
        desc->vdo |= DP_CAP_DP_SIGNALING | DP_CAP_RECEPTACLE;
 
@@ -296,12 +298,15 @@ struct typec_altmode *ucsi_register_displayport(struct ucsi_connector *con,
        desc->vdo |= all_assignments << 16;
 
        alt = typec_port_register_altmode(con->port, desc);
-       if (IS_ERR(alt))
+       if (IS_ERR(alt)) {
+               mutex_unlock(&con->lock);
                return alt;
+       }
 
        dp = devm_kzalloc(&alt->dev, sizeof(*dp), GFP_KERNEL);
        if (!dp) {
                typec_unregister_altmode(alt);
+               mutex_unlock(&con->lock);
                return ERR_PTR(-ENOMEM);
        }
 
@@ -314,5 +319,7 @@ struct typec_altmode *ucsi_register_displayport(struct ucsi_connector *con,
        alt->ops = &ucsi_displayport_ops;
        typec_altmode_set_drvdata(alt, dp);
 
+       mutex_unlock(&con->lock);
+
        return alt;
 }