Pretty scary stuff, even if you trust all of your users:

What's really amazing is that news of this vulnerability didn't really hit the mainstream web until today, but yet on Friday there was already a kernel patch. There's even an in-memory hotfix that you can use (I tried that too - it works) if you prefer to wait until an official kernel makes it downstream. Open source is amazing.

Had this been proprietary software, no one would have known about it except for the all the people exploiting it. Servers all over the world would get owned, and the software company wouldn't even discover it for a few more weeks. Or worse, they would know about it, but would hope to keep it hush-hush until the next Patch Tuesday.