From: Dirk Gouders Date: Tue, 21 May 2013 08:54:11 +0000 (+0200) Subject: kconfig/menu.c: fix multiple references to expressions in menu_add_prop() X-Git-Tag: 1.9.9~24 X-Git-Url: https://jxself.org/git/?a=commitdiff_plain;h=6cbac37e1eefd4d5f75879136cff03cdfd6c2e01;p=carl9170fw.git 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 [yann.morin.1998@free.fr: move variable into its block-scope, keep lines <80 chars, typo] Tested-by: "Yann E. MORIN" Reviewed-by: "Yann E. MORIN" Signed-off-by: "Yann E. MORIN" Signed-off-by: Christian Lamparter --- diff --git a/config/menu.c b/config/menu.c index b5c7d90..fd3f018 100644 --- a/config/menu.c +++ b/config/menu.c @@ -146,11 +146,24 @@ struct property *menu_add_prop(enum prop_type type, char *prompt, struct expr *e 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); } }