Bluetooth: Fix potential use-after-free when clear keys

Similar to commit c5d2b6fa26 ("Bluetooth: Fix use-after-free in
hci_remove_ltk/hci_remove_irk"). We can not access k after kfree_rcu()
call.

Fixes: d7d41682ef ("Bluetooth: Fix Suspicious RCU usage warnings")
Signed-off-by: Min Li <lm0963hack@gmail.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

net/bluetooth/hci_core.c

@@ -1074,9 +1074,9 @@ void hci_uuids_clear(struct hci_dev *hdev)
 
 void hci_link_keys_clear(struct hci_dev *hdev)
 {
-	struct link_key *key;
+	struct link_key *key, *tmp;
 
-	list_for_each_entry(key, &hdev->link_keys, list) {
+	list_for_each_entry_safe(key, tmp, &hdev->link_keys, list) {
 		list_del_rcu(&key->list);
 		kfree_rcu(key, rcu);
 	}
@@ -1084,9 +1084,9 @@ void hci_link_keys_clear(struct hci_dev *hdev)
 
 void hci_smp_ltks_clear(struct hci_dev *hdev)
 {
-	struct smp_ltk *k;
+	struct smp_ltk *k, *tmp;
 
-	list_for_each_entry(k, &hdev->long_term_keys, list) {
+	list_for_each_entry_safe(k, tmp, &hdev->long_term_keys, list) {
 		list_del_rcu(&k->list);
 		kfree_rcu(k, rcu);
 	}
@@ -1094,9 +1094,9 @@ void hci_smp_ltks_clear(struct hci_dev *hdev)
 
 void hci_smp_irks_clear(struct hci_dev *hdev)
 {
-	struct smp_irk *k;
+	struct smp_irk *k, *tmp;
 
-	list_for_each_entry(k, &hdev->identity_resolving_keys, list) {
+	list_for_each_entry_safe(k, tmp, &hdev->identity_resolving_keys, list) {
 		list_del_rcu(&k->list);
 		kfree_rcu(k, rcu);
 	}
@@ -1104,9 +1104,9 @@ void hci_smp_irks_clear(struct hci_dev *hdev)
 
 void hci_blocked_keys_clear(struct hci_dev *hdev)
 {
-	struct blocked_key *b;
+	struct blocked_key *b, *tmp;
 
-	list_for_each_entry(b, &hdev->blocked_keys, list) {
+	list_for_each_entry_safe(b, tmp, &hdev->blocked_keys, list) {
 		list_del_rcu(&b->list);
 		kfree_rcu(b, rcu);
 	}