[PATCH net 1/3] dpll: fix pin dump crash after module unbind

Disallow dump of unregistered parent pins, it is possible when parent
pin and dpll device registerer kernel module instance unbinds, and
other kernel module instances of the same dpll device have pins
registered with the parent pin. The user can invoke a pin-dump but as
the parent was unregistered, thus shall not be accessed by the
userspace, prevent that by checking if parent pin is still registered.

Fixes: 9d71b54b65b1 ("dpll: netlink: Add DPLL framework base functions")
Signed-off-by: Arkadiusz Kubalewski <arkadiusz.kubalewski@intel.com>
---
 drivers/dpll/dpll_netlink.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/dpll/dpll_netlink.c b/drivers/dpll/dpll_netlink.c
index a6dc3997bf5c..93fc6c4b8a78 100644
--- a/drivers/dpll/dpll_netlink.c
+++ b/drivers/dpll/dpll_netlink.c

@@ -328,6 +328,13 @@ dpll_msg_add_pin_parents(struct sk_buff *msg, struct dpll_pin *pin,
 		void *parent_priv;
 
 		ppin = ref->pin;
+		/*
+		 * dump parent only if it is registered, thus prevent crash on
+		 * pin dump called when driver which registered the pin unbinds
+		 * and different instance registered pin on that parent pin
+		 */
+		if (!xa_get_mark(&dpll_pin_xa, ppin->id, DPLL_REGISTERED))
+			continue;
 		parent_priv = dpll_pin_on_dpll_priv(dpll_ref->dpll, ppin);
 		ret = ops->state_on_pin_get(pin,
 					    dpll_pin_on_pin_priv(ppin, pin),

-- 
2.38.1