Re: [Qemu-devel] [PATCH] keymaps: detect recursive keyboard layout file

[Li Qiang <liq3ea@gmail.com>]

Markus Armbruster <armbru@redhat.com> 于2018年11月15日周四 下午9:29写道：

> Li Qiang <liq3ea@gmail.com> writes:
>
> > When the parse_keyboard_layout() find a "include " line
> > in the keyboard layout file, it will call parse_keyboard_layout()
> > to perform a recursive parse. If the keyboard layout is malformed
> > by adding a line include itself, this can cause an infinite parse.
> > Thus cause qemu a segv. This patch avoid this.
> >
> > Signed-off-by: Li Qiang <liq3ea@gmail.com>
> > ---
> >  ui/keymaps.c | 17 ++++++++++++++++-
> >  1 file changed, 16 insertions(+), 1 deletion(-)
> >
> > diff --git a/ui/keymaps.c b/ui/keymaps.c
> > index 085889b555..564893a9f3 100644
> > --- a/ui/keymaps.c
> > +++ b/ui/keymaps.c
> > @@ -38,6 +38,8 @@ struct kbd_layout_t {
> >      GHashTable *hash;
> >  };
> >
> > +GList *keyboard_files;
> > +
> >  static int get_keysym(const name2keysym_t *table,
> >                        const char *name)
> >  {
> > @@ -80,6 +82,11 @@ static void add_keysym(char *line, int keysym, int
> keycode, kbd_layout_t *k)
> >      trace_keymap_add(keysym, keycode, line);
> >  }
> >
> > +static gint compare_string(gconstpointer a, gconstpointer b)
> > +{
> > +    return g_strcmp0(a, b);
> > +}
> > +
> >  static int parse_keyboard_layout(kbd_layout_t *k,
> >                                   const name2keysym_t *table,
> >                                   const char *language, Error **errp)
> > @@ -94,12 +101,18 @@ static int parse_keyboard_layout(kbd_layout_t *k,
> >      filename = qemu_find_file(QEMU_FILE_TYPE_KEYMAP, language);
> >      trace_keymap_parse(filename);
> >      f = filename ? fopen(filename, "r") : NULL;
> > -    g_free(filename);
> >      if (!f) {
> > +        g_free(filename);
> >          error_setg(errp, "could not read keymap file: '%s'", language);
> >          return -1;
> >      }
> >
> > +    if (g_list_find_custom(keyboard_files, filename, compare_string)) {
> > +        error_setg(errp, "find recursive keyboard layout: %s'",
> filename);
>
> Suggest something like "Inclusion loop for %s".
>
> > +        g_free(filename);
> > +        return -1;
> > +    }
> > +    keyboard_files = g_list_append(keyboard_files, filename);
> >      for(;;) {
> >          if (fgets(line, 1024, f) == NULL) {
> >              break;
> > @@ -168,6 +181,8 @@ static int parse_keyboard_layout(kbd_layout_t *k,
> >      ret = 0;
> >  out:
> >      fclose(f);
> > +    keyboard_files = g_list_remove(keyboard_files, filename);
> > +    g_free(filename);
> >      return ret;
> >  }
>
> There's no real need to make @keyboard_files global.  I'd make it local
> to init_keyboard_layout(), and pass it as argument to
> parse_keyboard_layout().



Thanks Markus,
Finally, Gerd decide remove the support of "include" in keymaps.

Thanks,
Li Qiang


> Matter of taste.  Gerd is the maintainer, not
> me.
>