interconnect: Treat xlate() returning NULL node as an error

Currently, if provider->xlate() or provider->xlate_extended()
"successfully" return a NULL node, then of_icc_get_from_provider() won't
consider that an error and will successfully return the NULL node. This
bypasses error handling in of_icc_get_by_index() and leads to NULL
dereferences in path_find().

This could be avoided by ensuring provider callbacks always return an
error for NULL nodes, but it's better to explicitly protect against this
in the common framework.

Fixes: 87e3031 ("interconnect: Allow endpoints translation via DT")
Signed-off-by: Mike Tipton <quic_mdtipton@quicinc.com>
Link: https://lore.kernel.org/r/20231025145829.11603-1-quic_mdtipton@quicinc.com
Signed-off-by: Georgi Djakov <djakov@kernel.org>

Author: Mike Tipton

drivers/interconnect/core.c

@@ -395,6 +395,9 @@ struct icc_node_data *of_icc_get_from_provider(struct of_phandle_args *spec)
 	}
 	mutex_unlock(&icc_lock);
 
+	if (!node)
+		return ERR_PTR(-EINVAL);
+
 	if (IS_ERR(node))
 		return ERR_CAST(node);