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Subject[PATCH 4.9 045/329] kconfig: Dont leak main menus during parsing
Date
4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ulf Magnusson <ulfalizer@gmail.com>

[ Upstream commit 0724a7c32a54e3e50d28e19e30c59014f61d4e2c ]

If a 'mainmenu' entry appeared in the Kconfig files, two things would
leak:

- The 'struct property' allocated for the default "Linux Kernel
Configuration" prompt.

- The string for the T_WORD/T_WORD_QUOTE prompt after the
T_MAINMENU token, allocated on the heap in zconf.l.

To fix it, introduce a new 'no_mainmenu_stmt' nonterminal that matches
if there's no 'mainmenu' and adds the default prompt. That means the
prompt only gets allocated once regardless of whether there's a
'mainmenu' statement or not, and managing it becomes simple.

Summary from Valgrind on 'menuconfig' (ARCH=x86) before the fix:

LEAK SUMMARY:
definitely lost: 344,568 bytes in 14,352 blocks
...

Summary after the fix:

LEAK SUMMARY:
definitely lost: 344,440 bytes in 14,350 blocks
...

Signed-off-by: Ulf Magnusson <ulfalizer@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
scripts/kconfig/zconf.y | 33 ++++++++++++++++++++++++---------
1 file changed, 24 insertions(+), 9 deletions(-)

--- a/scripts/kconfig/zconf.y
+++ b/scripts/kconfig/zconf.y
@@ -107,7 +107,27 @@ static struct menu *current_menu, *curre
%%
input: nl start | start;

-start: mainmenu_stmt stmt_list | stmt_list;
+start: mainmenu_stmt stmt_list | no_mainmenu_stmt stmt_list;
+
+/* mainmenu entry */
+
+mainmenu_stmt: T_MAINMENU prompt nl
+{
+ menu_add_prompt(P_MENU, $2, NULL);
+};
+
+/* Default main menu, if there's no mainmenu entry */
+
+no_mainmenu_stmt: /* empty */
+{
+ /*
+ * Hack: Keep the main menu title on the heap so we can safely free it
+ * later regardless of whether it comes from the 'prompt' in
+ * mainmenu_stmt or here
+ */
+ menu_add_prompt(P_MENU, strdup("Linux Kernel Configuration"), NULL);
+};
+

stmt_list:
/* empty */
@@ -344,13 +364,6 @@ if_block:
| if_block choice_stmt
;

-/* mainmenu entry */
-
-mainmenu_stmt: T_MAINMENU prompt nl
-{
- menu_add_prompt(P_MENU, $2, NULL);
-};
-
/* menu entry */

menu: T_MENU prompt T_EOL
@@ -495,6 +508,7 @@ word_opt: /* empty */ { $$ = NULL; }

void conf_parse(const char *name)
{
+ const char *tmp;
struct symbol *sym;
int i;

@@ -502,7 +516,6 @@ void conf_parse(const char *name)

sym_init();
_menu_init();
- rootmenu.prompt = menu_add_prompt(P_MENU, "Linux Kernel Configuration", NULL);

if (getenv("ZCONF_DEBUG"))
zconfdebug = 1;
@@ -512,8 +525,10 @@ void conf_parse(const char *name)
if (!modules_sym)
modules_sym = sym_find( "n" );

+ tmp = rootmenu.prompt->text;
rootmenu.prompt->text = _(rootmenu.prompt->text);
rootmenu.prompt->text = sym_expand_string_value(rootmenu.prompt->text);
+ free((char*)tmp);

menu_finalize(&rootmenu);
for_all_symbols(i, sym) {

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