Which kernel versions does the udev exploit work? Upon googling this, I found articles claiming that it works on Android 2.1 and maybe 2.2, but there is no information about the kernel versions.
I'm actually not sure that the kernel version matters for this exploit. It was a bug that was patched in the platform_system_core repository, which I think comprises libraries and system files that live on in the
/system directory (the README says as much). The patch was committed on July 19, 2010 (in the Froyo branch, anyway).
I'd wager that any kernel with a build date later than that also has the updated system files, so the system wouldn't be vulnerable.
uname -a would tell you the build date of a given device's kernel, but beyond that I don't know that you could really line it up with a specific kernel version, especially on devices from different manufacturers/carriers/etc.