crash in newlocale()

[Corinna Vinschen]

On Aug 11 21:18, Takashi Yano wrote:
> On Thu, 11 Aug 2022 11:29:28 +1000
> Tony Cook wrote:
> > Hello everyone,
> > 
> > While tracking down a crash in development versions of perl the boostrap
> > miniperl executable was crashing early in the build process:
> > [...]
> 
> 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. */

I think the right thing to do is to avoid freeing this data, if the base
locale is the C locale.  I sent a patch to cygwin-patches for review.
Can you please take a look?


Thanks,
Corinna