Index: main/channel.c
===================================================================
--- main/channel.c	(revision 229008)
+++ main/channel.c	(working copy)
@@ -1128,6 +1128,8 @@
 {
 	struct ast_frame f = { AST_FRAME_CONTROL, };
 
+	ast_assert(datalen > 0 ? data != NULL : data == NULL);
+
 	f.subclass = control;
 	f.data.ptr = (void *) data;
 	f.datalen = datalen;
@@ -4818,7 +4820,7 @@
 			case AST_CONTROL_VIDUPDATE:
 			case AST_CONTROL_SRCUPDATE:
 			case AST_CONTROL_T38_PARAMETERS:
-				ast_indicate_data(other, f->subclass, f->data.ptr, f->datalen);
+				ast_indicate_data(other, f->subclass, f->datalen > 0 ? f->data.ptr : NULL, f->datalen);
 				if (jb_in_use) {
 					ast_jb_empty_and_reset(c0, c1);
 				}