Crispin Cowan <crispin@immunix.com> wrote: > Array bounds checking offers greater protection than any of these > protections (StackGuard, ProPolice, PointGuard, W^X, PAX/ASLR, etc.) The > problem is that the very fastest array bounds protection for C (Bounded > Pointers) imposes a 5X slowdown on performance, where as these other > techniques impose overheat somewhere between noise and 20%. This may be true. Doing "safe" pointers in C is difficult because of pointer arithmetic. But I think this is a bit unfair to bounds checking in general--type safe compiled languages like ML achieve array bounds checking (and other checks) at a much smaller penalty (less than 20% for array-oriented code in my experience). These languages also provide protection against other common sources of holes, like integer overflow, double-frees (most are garbage collected) and printf formatting attacks. This protection is automatic and absolute; the only thing left to worry about is bugs in the compiler, system library, and kernel (things that C programmers already need to worry about, anyway). In my opinion these languages are utterly practical for Unix network daemons. Of course, this is a bit more work because you don't just recompile the program, you have to rewrite it from scratch! But there are other benefits to maintaining code in a modern, safe, high-level language. - Tom [ http://www.cs.cmu.edu/~tom7/ ]
