Upgrading to glibc 2.3.4 on a Debian system will make your system nearly unusable. Due to RedHat's fundamentally flawed PT_GNU_STACK implementation, many packages have their libraries marked as needing executable stacks, when such executable stacks are not needed. I've filed bug reports with Debian, but they are not taking the issue seriously. Here's one of their replies:
> What do you propose be done then until all the apps in this list (and
> more) are fixed:
That's not much of a list; I'm not overly concerned.
> I don't know how Debian handles large issues like this, but this is
> something every package maintainer needs to be aware of quickly.
> If Debian doesn't act soon, they'll be releasing many advisories of this
> and be getting many complaints from PaX users because their system is
> now unusable.
Guess what? Debian does not support PaX.
I urge everyone to contact Debian and make them take this issue seriously, otherwise your systems will soon become unusable.