crash in newlocale()
Takashi Yano
takashi.yano@nifty.ne.jp
Thu Aug 11 23:41:28 GMT 2022
On Thu, 11 Aug 2022 12:29:31 -0400
Ken Brown wrote:
> On 8/11/2022 8:18 AM, Takashi Yano wrote:
> > On Thu, 11 Aug 2022 11:29:28 +1000
> > Tony Cook wrote:
> >> $ cat newlocale-test.c
> >> #include <locale.h>
> >> #include <stdio.h>
> >>
> >> int main() {
> >> locale_t st = newlocale(LC_ALL_MASK, "C", (locale_t)0);
> >>
> >> locale_t st2 = newlocale(LC_CTYPE_MASK, "en_US.UTF-8", st);
> >> printf("Done\n");
> >> return 0;
> >> }
> >> Program terminated with signal SIGTRAP, Trace/breakpoint trap.
> >> The program no longer exists.
> >> (gdb)
> >
> > I looked into this problem and found the access violation
> > occurs at:
> > newlib/libc/locale/newlocale.c
> > @@ 188,7 @@ _newlocale_r (struct _reent *p, int category_mask, const char *locale,
> > if (tmp_locale.lc_cat[i].buf == (const void *) -1)
> > {
> > tmp_locale.lc_cat[i].buf = base->lc_cat[i].buf;
> > base->lc_cat[i].ptr = base->lc_cat[i].buf = NULL; <-- Here!!!
> > }
> > #endif /* __HAVE_LOCALE_INFO__ */
> > _freelocale_r (p, base);
> >
> > This is because
> > locale_t st = newlocale(LC_ALL_MASK, "C", (locale_t)0);
> > returns
> > extern const struct __locale_t __C_locale;
> > return (struct __locale_t *) &__C_locale;
> > , which is in the const area that cannot be modified.
> >
> > This seems to be a newlib bug.
> >
> > I also found following patch solves the issue.
> >
> > diff --git a/newlib/libc/locale/newlocale.c b/newlib/libc/locale/newlocale.c
> > index 0789d5fd9..1974665ec 100644
> > --- a/newlib/libc/locale/newlocale.c
> > +++ b/newlib/libc/locale/newlocale.c
> > @@ -108,10 +108,12 @@ _newlocale_r (struct _reent *p, int category_mask, const char *locale,
> > }
> > /* If the new locale is supposed to be all default locale, just return
> > a pointer to the default locale. */
> > +#if 0
> > if ((!base && category_mask == 0)
> > || (category_mask == LC_VALID_MASK
> > && (!strcmp (locale, "C") || !strcmp (locale, "POSIX"))))
> > return __get_C_locale ();
> > +#endif
> > /* Start with setting all values to the default locale values. */
> > tmp_locale = *__get_C_locale ();
> > /* Fill out new category strings. */
>
> Good work tracking this down!
>
> I was about to suggest that instead of just disabling this optimization, you
> call _duplocale_r to return a duplicate of __get_C_locale (). But then I saw
> the following in the definition of _duplocale_r in duplocale.c:
>
> /* The "C" locale is used statically, never copied. */
> else if (locobj == __get_C_locale ())
> return __get_C_locale ();
>
> This looks like another bug. Shouldn't duplocale always return a modifiable object?
Thanks!
Corinna's patch avoids the problem also for this case.
--
Takashi Yano <takashi.yano@nifty.ne.jp>
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