6.1-stable review patch. If anyone has any objections, please let me know.
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From: Xu Yang xu.yang_2@nxp.com
commit 1c9be13846c0b2abc2480602f8ef421360e1ad9e upstream.
In current design, usb role class driver will get usb_role_switch parent's module reference after the user get usb_role_switch device and put the reference after the user put the usb_role_switch device. However, the parent device of usb_role_switch may be removed before the user put the usb_role_switch. If so, then, NULL pointer issue will be met when the user put the parent module's reference.
This will save the module pointer in structure of usb_role_switch. Then, we don't need to find module by iterating long relations.
Fixes: 5c54fcac9a9d ("usb: roles: Take care of driver module reference counting") cc: stable@vger.kernel.org Signed-off-by: Xu Yang xu.yang_2@nxp.com Acked-by: Heikki Krogerus heikki.krogerus@linux.intel.com Link: https://lore.kernel.org/r/20240129093739.2371530-1-xu.yang_2@nxp.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/roles/class.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-)
--- a/drivers/usb/roles/class.c +++ b/drivers/usb/roles/class.c @@ -19,6 +19,7 @@ static struct class *role_class; struct usb_role_switch { struct device dev; struct mutex lock; /* device lock*/ + struct module *module; /* the module this device depends on */ enum usb_role role;
/* From descriptor */ @@ -133,7 +134,7 @@ struct usb_role_switch *usb_role_switch_ usb_role_switch_match);
if (!IS_ERR_OR_NULL(sw)) - WARN_ON(!try_module_get(sw->dev.parent->driver->owner)); + WARN_ON(!try_module_get(sw->module));
return sw; } @@ -155,7 +156,7 @@ struct usb_role_switch *fwnode_usb_role_ sw = fwnode_connection_find_match(fwnode, "usb-role-switch", NULL, usb_role_switch_match); if (!IS_ERR_OR_NULL(sw)) - WARN_ON(!try_module_get(sw->dev.parent->driver->owner)); + WARN_ON(!try_module_get(sw->module));
return sw; } @@ -170,7 +171,7 @@ EXPORT_SYMBOL_GPL(fwnode_usb_role_switch void usb_role_switch_put(struct usb_role_switch *sw) { if (!IS_ERR_OR_NULL(sw)) { - module_put(sw->dev.parent->driver->owner); + module_put(sw->module); put_device(&sw->dev); } } @@ -187,15 +188,18 @@ struct usb_role_switch * usb_role_switch_find_by_fwnode(const struct fwnode_handle *fwnode) { struct device *dev; + struct usb_role_switch *sw = NULL;
if (!fwnode) return NULL;
dev = class_find_device_by_fwnode(role_class, fwnode); - if (dev) - WARN_ON(!try_module_get(dev->parent->driver->owner)); + if (dev) { + sw = to_role_switch(dev); + WARN_ON(!try_module_get(sw->module)); + }
- return dev ? to_role_switch(dev) : NULL; + return sw; } EXPORT_SYMBOL_GPL(usb_role_switch_find_by_fwnode);
@@ -337,6 +341,7 @@ usb_role_switch_register(struct device * sw->set = desc->set; sw->get = desc->get;
+ sw->module = parent->driver->owner; sw->dev.parent = parent; sw->dev.fwnode = desc->fwnode; sw->dev.class = role_class;