Re: Backwards compatibility
Sorry, I believed you were the OP of the comment I answered. My fault.
Vector fonts are trickier to handle because you don't just shuffle pixel around - you actually need to calculate what pixels to show and how (because of antialising, kerning, etc.) - and to display text - often a lot of text - there's a lot of work to be done under the hood. Userland code can't write to buffers in kernel, and code from kernel still will go through the protected mode access checks wherever accessing userland buffers from kernel code slowing that down.
Moreover, users wants to exploit their expensive graphic card GPUs... you got Direct 2D and hardware accelerated browser rendering - browser are today one of the applications - being UI intensive - that got the most benefit from a more performant UI code.
Anyway this wasn't a bug due to fonts - it's how the scrollbat kernel code accepts data from userland without proper checks. It just allows to flip a couple of bits - but it's enogh to trigger a buffer overflow if properly exploited.
Biting the hand that feeds IT
