You get the source code to udev from kernel.org. It's located in the pub/linux/utils/kernel/hotplug directory. Here's a direct link:
There's a README file in the tarball that discusses prerequisites for the kernel config (which you should meet if you were using udev previously), and describes how to make the project.
I do not know
if there are any special precautions you need to take when overwriting an existing udev installation. It might be worth your while to do some Google searching about that.
Also, I'm just providing info based on what foo_bar_foo suggested. I don't know whether this will fix your problem or not; it's just information on how to get a more recent copy of udev.