whoopsie regression

USN-4170-1 fixed a vulnerability in Whoopsie and USN-4170-2 fixed a
subsequent regression. That update was incomplete and could still result in
Whoopsie potentially crashing when uploading crash reports on some
architectures. This update fixes the problem.

We apologize for the inconvenience.

Original advisory details:

Kevin Backhouse discovered Whoopsie incorrectly handled very large crash
reports. A local attacker could possibly use this issue to cause a denial
of service, expose sensitive information or execute code as the whoopsie
user.