[PATCH v2] posix: Avoid a stack overflow when glob is given many trailing slashes [BZ #30635]

[Collin Funk]

Florian Weimer <fweimer@redhat.com> writes:

> * Andreas Schwab:
>
>> On Okt 07 2025, Collin Funk wrote:
>>
>>> diff --git a/posix/glob.c b/posix/glob.c
>>> index a7c7dd1ebe..82ee873d80 100644
>>> --- a/posix/glob.c
>>> +++ b/posix/glob.c
>>> @@ -596,6 +596,10 @@ __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
>>>                    flags &= ~(GLOB_NOCHECK | GLOB_NOMAGIC);
>>>                  }
>>>              }
>>> +          /* Prevent stack overflows with many trailing '/' characters.  */
>>> +          for (char *p = &dirname[dirlen - 1];
>>> +               dirname < p && p[0] == '/' && p[-1] == '/'; --p)
>>                   p > dirname
>
> See <https://www.enyo.de/fw/notes/style-guide-conditions.html>
> for some background.

I'll change it locally.

Thanks,
Collin