+/**
+ * binder_get_node_refs_for_txn() - Get required refs on node for txn
+ * @node: struct binder_node for which to get refs
+ * @proc: returns @node->proc if valid
+ * @error: if no @proc then returns BR_DEAD_REPLY
+ *
+ * User-space normally keeps the node alive when creating a transaction
+ * since it has a reference to the target. The local strong ref keeps it
+ * alive if the sending process dies before the target process processes
+ * the transaction. If the source process is malicious or has a reference
+ * counting bug, relying on the local strong ref can fail.
+ *
+ * Since user-space can cause the local strong ref to go away, we also take
+ * a tmpref on the node to ensure it survives while we are constructing
+ * the transaction. We also need a tmpref on the proc while we are
+ * constructing the transaction, so we take that here as well.
+ *
+ * Return: The target_node with refs taken or NULL if no @node->proc is NULL.
+ * Also sets @proc if valid. If the @node->proc is NULL indicating that the
+ * target proc has died, @error is set to BR_DEAD_REPLY
+ */
+static struct binder_node *binder_get_node_refs_for_txn(
+ struct binder_node *node,
+ struct binder_proc **procp,
+ uint32_t *error)
+{
+ struct binder_node *target_node = NULL;
+
+ binder_node_inner_lock(node);
+ if (node->proc) {
+ target_node = node;
+ binder_inc_node_nilocked(node, 1, 0, NULL);
+ binder_inc_node_tmpref_ilocked(node);
+ node->proc->tmp_ref++;
+ *procp = node->proc;
+ } else
+ *error = BR_DEAD_REPLY;
+ binder_node_inner_unlock(node);
+
+ return target_node;
+}
+