full-disclosure - Re: [FD] getenv("=A") works (no particular vulnerability)

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Date: Sat, 5 Feb 2022 07:10:03 +0000
From: bo0od via Fulldisclosure <fulldisclosure@...lists.org>
To: fulldisclosure@...lists.org
Subject: Re: [FD] getenv("=A") works (no particular vulnerability)

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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