diff --git a/scripts/kconfig/conf.c b/scripts/kconfig/conf.c
index c368bec5ab60..fe8ba09b0039 100644
--- a/scripts/kconfig/conf.c
+++ b/scripts/kconfig/conf.c
@@ -348,6 +348,23 @@ static int conf_string(struct menu *menu)
 		}
 		if (def && sym_set_string_value(sym, def))
 			return 0;
+
+		/*
+		 * A new int or hex symbol whose default fails validation
+		 * cannot be set from an empty answer. When standard input is
+		 * exhausted, as it is for a non-interactive oldconfig or
+		 * syncconfig, re-asking would loop forever and grow the output
+		 * until it exhausts memory. Stop with an error that names the
+		 * symbol instead. String symbols accept any text, and bool and
+		 * tristate symbols (conf_sym()) and choices (conf_choice())
+		 * accept the default on an empty line, so they are unaffected.
+		 */
+		if (feof(stdin)) {
+			fprintf(stderr,
+				"\nerror: no value for new symbol '%s' at end of input\n",
+				sym->name);
+			exit(1);
+		}
 	}
 }