ieee802154: hwsim: Fix possible memory leaks

After replacing e->info, it is necessary to free the old einfo.

Fixes: f25da51 ("ieee802154: hwsim: add replacement for fakelb")
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: Chen Aotian <chenaotian2@163.com>
Link: https://lore.kernel.org/r/20230409022048.61223-1-chenaotian2@163.com
Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>

Author: Chen Aotian

drivers/net/ieee802154/mac802154_hwsim.c

@@ -685,7 +685,7 @@ static int hwsim_del_edge_nl(struct sk_buff *msg, struct genl_info *info)
 static int hwsim_set_edge_lqi(struct sk_buff *msg, struct genl_info *info)
 {
 	struct nlattr *edge_attrs[MAC802154_HWSIM_EDGE_ATTR_MAX + 1];
-	struct hwsim_edge_info *einfo;
+	struct hwsim_edge_info *einfo, *einfo_old;
 	struct hwsim_phy *phy_v0;
 	struct hwsim_edge *e;
 	u32 v0, v1;
@@ -723,8 +723,10 @@ static int hwsim_set_edge_lqi(struct sk_buff *msg, struct genl_info *info)
 	list_for_each_entry_rcu(e, &phy_v0->edges, list) {
 		if (e->endpoint->idx == v1) {
 			einfo->lqi = lqi;
-			rcu_assign_pointer(e->info, einfo);
+			einfo_old = rcu_replace_pointer(e->info, einfo,
+							lockdep_is_held(&hwsim_phys_lock));
 			rcu_read_unlock();
+			kfree_rcu(einfo_old, rcu);
 			mutex_unlock(&hwsim_phys_lock);
 			return 0;
 		}