oss-sec mailing list archives

Re: RFC: changing the behaviour of ld.so(8) regarding empty items on LD_LIBRARY_PATH


From: Tim Brown <timb () nth-dimension org uk>
Date: Wed, 29 Sep 2010 07:08:10 +0100

On Wednesday 29 September 2010 00:42:05 Raphael Geissert wrote:
Hi everyone,

I have talked to one of the eglibc Debian maintainers about making ld.so
ignore empty items on LD_LIBRARY_PATH instead of treating them as '.', and
he doesn't have any objection.

Although this is a behaviour change, I do not think there is any real case
where an empty item was added in purpose (I even have yet to see one that
uses '.'.)
We are therefore considering making this change starting with our next
stable release.

What do the others think about it? do you think you would follow that
change too?

This change has been proposed by some people multiple times along the
years, yet nothing has changed (not even properly discussed, I believe.)
Has this change ever been proposed to glibc upstream? (maybe the RedHat
people can help with this.)


There is a similar issue with $PATH, but we have no plans for it so far
(execvp(8) claims ":/bin:/usr/bin" is the default if $PATH is unset, in
some setups.)

You have my vote, I proposed the very same on oss-security a couple of weeks 
back (http://www.openwall.com/lists/oss-security/2010/08/29/4).  I'm actually 
working on a paper about exploiting the linker at the moment (seems many 
people don't fully understand it), I'll be more than happy to share it when 
it's complete.

Tim
-- 
Tim Brown
<mailto:timb () nth-dimension org uk>
<http://www.nth-dimension.org.uk/>

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