[PATCH 6.1 124/195] usb: roles: fix NULL pointer issue when put modules reference

Greg Kroah-Hartman
2024-02-27T14:18:04Z

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;