kconfig/menu.c: fix multiple references to expressions in menu_add_prop()
menu_add_prop() applies upper menus' visibilities to actual prompts
by AND-ing the prompts visibilities with the upper menus ones.
This creates a further reference to the menu's visibilities and when
the expression reduction functions do their work, they may remove or
modify expressions that have multiple references, thus causing
unpredictable side-effects.
The following example Kconfig constructs a case where this causes
problems: a menu and a prompt which's visibilities depend on the same
symbol. When invoking mconf with this Kconfig and pressing "Z" we
see a problem caused by a free'd expression still referenced by the
menu's visibility:
------------------------------------------------------------------------
mainmenu "Kconfig Testing Configuration"
config VISIBLE
def_bool n
config Placeholder
bool "Place holder"
menu "Invisible"
visible if VISIBLE
config TEST_VAR
bool "Test option" if VISIBLE
endmenu
------------------------------------------------------------------------
This patch fixes this problem by creating copies of the menu's
visibility expressions before AND-ing them with the prompt's one.
Signed-off-by: Dirk Gouders <dirk@gouders.net>
[yann.morin.1998@free.fr: move variable into its block-scope,
keep lines <80 chars, typo]
Tested-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
diff --git a/scripts/kconfig/menu.c b/scripts/kconfig/menu.c
index b5c7d90..fd3f018 100644
--- a/scripts/kconfig/menu.c
+++ b/scripts/kconfig/menu.c
@@ -146,11 +146,24 @@
struct menu *menu = current_entry;
while ((menu = menu->parent) != NULL) {
+ struct expr *dup_expr;
+
if (!menu->visibility)
continue;
+ /*
+ * Do not add a reference to the
+ * menu's visibility expression but
+ * use a copy of it. Otherwise the
+ * expression reduction functions
+ * will modify expressions that have
+ * multiple references which can
+ * cause unwanted side effects.
+ */
+ dup_expr = expr_copy(menu->visibility);
+
prop->visible.expr
= expr_alloc_and(prop->visible.expr,
- menu->visibility);
+ dup_expr);
}
}