getpwent_r(3) needs gr->gr_mem to be freed, but that's not documented

[Collin Funk]

Cristian Rodríguez <cristian@rodriguez.im> writes:

> On Sun, Sep 28, 2025 at 5:40 PM Alejandro Colomar <alx@kernel.org> wrote:
>>
>> On Sun, Sep 28, 2025 at 10:26:33PM +0200, Alejandro Colomar wrote:
>> > Hi!
>> >
>> > Another thing I realized about getpwent_r(3) et al. is that gr->gr_mem
>>
>> Actually, getgrent_r(3).
>>
>> > is allocated by the function, but is expected to be freed by the caller.
>> >
>> > I didn't find this documented, neither in the manual page nor in the
>> > glibc manual.  Is it documented but I missed it?  Or did I misunderstand
>> > something?  Or is it just that nobody documented it?
>
> It is just not documented it seems, that's great..another footgun..

POSIX also doesn't require the gr_mem member be allocated using malloc.

Collin