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kconfig: Clean up modules handling and fix crash

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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 <ulfalizer@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
This commit is contained in:
Ulf Magnusson 2017-10-05 14:01:15 +02:00 committed by Masahiro Yamada
parent fa8cedaef8
commit f77850d3fe
1 changed files with 6 additions and 4 deletions
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10
scripts/kconfig/menu.c
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@ -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)