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    Subject[PATCH AUTOSEL for 4.9 232/293] kconfig: Don't leak main menus during parsing
    Date
    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>
    ---
    scripts/kconfig/zconf.y | 33 ++++++++++++++++++++++++---------
    1 file changed, 24 insertions(+), 9 deletions(-)

    diff --git a/scripts/kconfig/zconf.y b/scripts/kconfig/zconf.y
    index 71bf8bff696a..5122ed2d839a 100644
    --- a/scripts/kconfig/zconf.y
    +++ b/scripts/kconfig/zconf.y
    @@ -107,7 +107,27 @@ static struct menu *current_menu, *current_entry;
    %%
    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) {
    --
    2.15.1
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