kconfig: don't crash on NULL expressions in expr_eq()

[carl9170fw.git] / config / expr.c

diff --git a/config/expr.c b/config/expr.c
index 3ff8c92c86baf925f866db5b1307c0e53ba08628..9f1de58e9f0c995fba0a0a0cf076be4a18e79ca1 100644 (file)
--- a/config/expr.c
+++ b/config/expr.c
@@ -3,6 +3,8 @@
  * Copyright (C) 2002 Roman Zippel <zippel@linux-m68k.org>
  */
 
+#include <ctype.h>
+#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -252,6 +254,13 @@ static int expr_eq(struct expr *e1, struct expr *e2)
 {
        int res, old_count;
 
+       /*
+        * A NULL expr is taken to be yes, but there's also a different way to
+        * represent yes. expr_is_yes() checks for either representation.
+        */
+       if (!e1 || !e2)
+               return expr_is_yes(e1) && expr_is_yes(e2);
+
        if (e1->type != e2->type)
                return 0;
        switch (e1->type) {