I'm not sure what the problem would be. Seems like Tesla uses Linux and the Linux kernel is worked on by thousands of people around the world. It is the largest software project in the world, run on more devices than anything else. It has proven to be very secure.
the kernel is pretty secure IF you keep up with the upstream patches (no idea if tesla does; my guess is that they, like most of the vendors that use linux, do NOT keep up with all the updates and have a guy (or even better, more than 1) who decides what version of this lib or that app they take. they have to test it and lock it down (the changes) and only permit changes they agree with and have tested (and feel safe about). that's a lot of work and most companies do NOT do this (very sad to say that but its true, and its my experience in the industry; 25+ years in bay area, etc)
userland is another story, altogether ([airplane]
userland is another story[/airplane]). there are bugs and they sometimes go a long time before being found. I use linux, have been for quite a long time, I love it, but I also realize that its not the right tool for safety-critical things unless you take significant pains (MISRA, anyone?). I have my doubts as to how well tesla does all this (I have not seen any of their code, and frankly, don't want to). but I have a hunch that there are some major security holes that a good pen-testing team would find. thru CAN, thru LIN, thru places you may not even expect. I've seen it, indirectly, and it amazed me.
I'm a VERY open source person, but for cars (a field I work in, currently) I'm not sure I agree. there are even lower level OSs than linux that have more safety certification-based designs and limitations (limits are good, for embedded).
besides all that, to be really effective at working on car systems that have so many dependancies, you have to be 'in' the group, have good access to info and even then its a challenge
this is not for outsiders and its hard enough to manage insiders.
