From a542100e78834c07080b393b00484fc2be46212f Mon Sep 17 00:00:00 2001 From: Ulf Magnusson Date: Thu, 5 Oct 2017 14:01:15 +0200 Subject: [PATCH] kconfig: Clean up modules handling and fix crash Kconfig currently doesn't handle 'm' appearing in a Kconfig file before the modules symbol is defined (the symbol with 'option modules'). The problem is the following code, which runs during parsing: /* change 'm' into 'm' && MODULES */ if (e->left.sym == &symbol_mod) return expr_alloc_and(e, expr_alloc_symbol(modules_sym)); If the modules symbol has not yet been defined, modules_sym is NULL, giving an invalid expression. Here is a test file where both BEFORE_1 and BEFORE_2 trigger a segfault. If the modules symbol is removed, all symbols trigger segfaults. config BEFORE_1 def_tristate y if m if m config BEFORE_2 def_tristate y endif config MODULES def_bool y option modules config AFTER_1 def_tristate y if m if m config AFTER_2 def_tristate y endif Fix the issue by rewriting 'm' in menu_finalize() instead. This function runs after parsing and is the proper place to do it. The following existing code in conf_parse() in zconf.y ensures that the modules symbol exists at that point: if (!modules_sym) modules_sym = sym_find( "n" ); ... menu_finalize(&rootmenu); The following tests were done to ensure no functional changes for configurations that don't reference 'm' before the modules symbol: - zconfdump(stdout) was run with ARCH=x86 and ARCH=arm before and after the change and verified to produce identical output. This function prints all symbols, choices, and menus together with their properties and their dependency expressions. A rewritten 'm' appears as 'm && MODULES'. A small annoyance is that the assert(len != 0) in xfwrite() needs to be disabled in order to use zconfdump(), because it chokes on e.g. 'default ""'. - The Kconfiglib test suite was run to indirectly verify that alldefconfig, allyesconfig, allnoconfig, and all defconfigs in the kernel still generate the same final .config. - Valgrind was used to check for memory errors and (new) memory leaks. Signed-off-by: Ulf Magnusson Signed-off-by: Masahiro Yamada Signed-off-by: Christian Lamparter --- config/menu.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/config/menu.c b/config/menu.c index c8cec26..2baebe3 100644 --- a/config/menu.c +++ b/config/menu.c @@ -110,7 +110,7 @@ static struct expr *rewrite_m(struct expr *e) void menu_add_dep(struct expr *dep) { - current_entry->dep = expr_alloc_and(current_entry->dep, rewrite_m(dep)); + current_entry->dep = expr_alloc_and(current_entry->dep, dep); } void menu_set_type(int type) @@ -135,7 +135,7 @@ static struct property *menu_add_prop(enum prop_type type, char *prompt, struct prop->menu = current_entry; prop->expr = expr; - prop->visible.expr = rewrite_m(dep); + prop->visible.expr = dep; if (prompt) { if (isspace(*prompt)) { @@ -340,7 +340,8 @@ void menu_finalize(struct menu *parent) * Propagate parent dependencies to the child menu * node, also rewriting and simplifying expressions */ - basedep = expr_transform(menu->dep); + basedep = rewrite_m(menu->dep); + basedep = expr_transform(basedep); basedep = expr_alloc_and(expr_copy(parentdep), basedep); basedep = expr_eliminate_dups(basedep); menu->dep = basedep; @@ -383,7 +384,8 @@ void menu_finalize(struct menu *parent) * property's condition, rewriting and * simplifying expressions at the same time */ - dep = expr_transform(prop->visible.expr); + dep = rewrite_m(prop->visible.expr); + dep = expr_transform(dep); dep = expr_alloc_and(expr_copy(basedep), dep); dep = expr_eliminate_dups(dep); if (menu->sym && menu->sym->type != S_TRISTATE) -- 2.31.1