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

[Florian Weimer]

* 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.

Thanks,
Florian