From: "Omar Polo" <op@omarpolo.com>
Subject: Re: leak in mg, interpreter.c:599
To: Han Boetes <hboetes@gmail.com>
Cc: tech@openbsd.org
Date: Sun, 22 Feb 2026 11:34:47 +0100

Hello,

Han Boetes <hboetes@gmail.com> wrote:
> While playing around with valgrind and mg I noticed some leaks.
> First, I created a test init-file with the contents:
> 
> (define myvar "hello")
> (define myvar "world")
> 
> After which something is leaking in interpreter.c at line 599, see 
> valgrind output below.
> 
> Upon redefinition of a variable, the old varentry and its v_name string 
> are not freed. Additionally, SLIST_INSERT_HEAD is called before strndup 
> succeeds, meaning a failed strndup leaves a partially initialised entry 
> in the live list.
> The following patch fixes both issues. With it applied, the 
> interpreter.c leak in the valgrind output below disappears.

Thanks for the diff!

I was a bit confused why v_vals was not freed as well, but it seems it's
never used (just set to NULL), so I've left it as-is for now.

Just fyi: the diff was mangled by the mua, and the indentation seemed a
bit off, so I had to hand-apply it.


Thanks!
Omar Polo