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Date: Wed, 06 Oct 2021 11:31:29 +0200
From: Pablo Correa Gomez <>
Subject: newlocale: Segmentation fault when locale input is NULL

Dear musl maintainers,

While doing some work in GNOME control center for postmarketos, we
bumped into a segmentation fault which is also present in GNOME in

After doing some degugging, I figured out that the reason is that,
through GNOME desktop[2], there is a call to newlocale, where they end
up calling it with a NULL argument.

newlocale(LC_CTYPE, NULL, (locale_t)0);

In this case, "name" is passed to __get_locale in
src/locale/newlocale.c:27 and then dereferenced in
src/locale/locale_map.c:43, causing a segmentation fault.

In the case of glibc, this is not an issue, as per the documentation[3]
they consider it an error:

       EINVAL locale is NULL.

Unfortunately, this is a difference in the implementation between glibc
and musl, maybe due to the fact that the standard[4] in not clear in
this point:

The newlocale() function may fail if:

    The locale argument is not a valid string pointer. 

My personal believe is that adding a NULL pointer check in musl is very
simple and might help not only GNOME desktop, but maybe also other
projects in the future. This is the reason why I brought the issue here
first instead of directly patching GNOME desktop. If you believe that
musl behaviour should remain the way it is, please let me know and I
will send MRs for upstream and Alpine's GNOME desktop. I am not
subscribed to the mailing list, so I would appreciate if I am CC'ed in
any response.

Best regards,
Pablo Correa Gómez.


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