Full Disclosure mailing list archives

Re: getenv("=A") works (no particular vulnerability)


From: bo0od via Fulldisclosure <fulldisclosure () seclists org>
Date: Sat, 5 Feb 2022 07:10:03 +0000

post it to glibc (there are devs,ticket system, community..)

https://www.gnu.org/software/libc/

Askar Safin via Fulldisclosure:
TL;DR: this mail doesn't contain any actual vulnerability, just an idea.

Consider this C code for Linux and glibc:

---------
#define _GNU_SOURCE 1
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
char *new_env[] = {"=A=B", 0};
int
main ()
{
   environ = new_env;
   printf("%s\n", getenv("=A")); // prints "B"
   return 0;
}
---------

This code prints "B". I. e. glibc allows variables starting with "=". It is quite possible such behavior can lead to 
various vulnerabilities.

It is possible this list is inappropriate for such message. If so, please, say, where I should post such message next 
time.

==
Askar Safin
http://safinaskar.com
https://sr.ht/~safinaskar
https://github.com/safinaskar

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