Date: Sat, 15 Jun 2002 00:50:03 -0700 (PDT) From: David Greenman-Lawrence <dg@root.com> To: freebsd-bugs@FreeBSD.org Subject: Re: misc/39314: Memory leak in setenv Message-ID: <200206150750.g5F7o3O07077@freefall.freebsd.org>
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The following reply was made to PR misc/39314; it has been noted by GNATS.
From: David Greenman-Lawrence <dg@root.com>
To: Nathan Mower <nmower@verio.net>
Cc: freebsd-gnats-submit@FreeBSD.org
Subject: Re: misc/39314: Memory leak in setenv
Date: Sat, 15 Jun 2002 00:44:45 -0700
>>Description:
> There is a memory leak in setenv in the case where a name/value pair already exists and the new value is larger than the old one. Setenv does not free the old memory before it malloc's space for the new string.
>>How-To-Repeat:
> setenv("HOME", "/usr/home/abc", 1);
> setenv("HOME", "/usr/home/abcdefghijklmnopqrstuvwxyz", 1);
>>Fix:
> free the old environ[offset] before malloc'ing the new one.
This is a well known and unfixable problem. The problem is that
environment data may not (and often is not) allocated by malloc - you
just don't know, so you can't free it. This is mentioned in the BUGS
section in the setenv.3 manual page, although the description of
the problem is misleading.
-DG
D.G.Lawrence
Download Technologies, Inc. - http://www.downloadtech.com - (866) 399 8500
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