A view from the inside.... sort-of
>>I wonder if they had a control group of projects which they ran Coverity on and which they didn't report any of the flaws that they found?
They scan projects that people suggest to them. From whats visible they _might_ use the projects which don't officially sign up developers to get reports as a baseline of the general environment. Would be biased though since they are likely to be the small ones.
>> Do you know ANY OS/commercial project that has 39 million LOC?
From the weird results I've had to wade through to find the bugs sometimes it seems to me that they scan the latest release of all available versions of the project. So you have to divide that 39M again by the number of active supported releases.
... or maybe the billion is the aggregate number of scans run (at one per day or so).
The largest project on their list is KDE with over 4 Mega lines. You can see the project list at http://scan.coverity.com/rungAll.html
>> You only get the full benefit if you mark up the OS headers, too, which isn't going to happen for the vast majority of people
It's annoying but I suppose useful, coverity report any OS flaws that are in code used by the FOSS project and count them against the project itself. Though I suppose it increases the pressure from app devs to the OS devs to get the OS fixed too, and get app devs to migrate to safer libraries.