Exit on error when asking for value that has an invalid default value
and stdin is closed. Previously, this case would loop.

Signed-off-by: Yoann Congal <yoann.congal@smile.fr>
---
 scripts/kconfig/conf.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/scripts/kconfig/conf.c b/scripts/kconfig/conf.c
index 33d19e419908b..38ff9c81e071d 100644
--- a/scripts/kconfig/conf.c
+++ b/scripts/kconfig/conf.c
@@ -376,6 +376,15 @@ static int conf_string(struct menu *menu)
 		}
 		if (def && sym_set_string_value(sym, def))
 			return 0;
+		else {
+			if (feof(stdin) && !sym_string_valid(sym, sym_get_string_value(sym))) {
+				fprintf(stderr,
+						"Symbol %s has invalid default value and stdin reached EOF\n",
+						sym->name);
+				exit(1);
+			}
+		}
+
 	}
 }
 
-- 
2.30.2