Diehard allocator - custom allocators, Operating System

Allocators can also be used to avoid problems with unsafe languages. C and C++ are pervasive, with huge amounts of existing code. They are also memory-unsafe languages, in that they allow many errors and security vulnerabilities. Some examples include double free(), invalid free(), uninitialized reads, dangling pointers, and buffer over?ows in both stack and heap buffers.

DieHard is an allocator developed at UMass which provides (or at least improves) soundness for erroneous programs. There are several hardware trends which are occurring: multicore processors are becoming the norm, physical memory is relatively inexpensive, and 64-bit architectures are increasingly common, with huge virtual address spaces. Meanwhile, most programs have trouble making full use of multiple processors. The net result is that there may soon be unused processing power and enormous virtual address spaces.

If you had an in?nite address space, you wouldn't have to worry about freeing objects. That would mostly eliminate the double free(), invalid free(), and dangling pointer bugs. And if your heap objects were in?nitely far apart in memory, you wouldn't need to worry about buffer over?ows in heap objects.

DieHard tries to provide something along these lines, within the constraints of ?nite physical memory. It uses randomized heap allocation, so objects are not necessarily contiguous in virtual memory. Since the address space is actually ?nite, objects won't actually be in?nitely far apart, and buffer overruns might actually cause collisions between heap objects. But this is where the multicore processors come in: With the unused processor cores, run multiple copies of the application, say three copies, each allocating into their own randomized heap. So the heap errors are independent among the three copies of the application. All copies get the same input, and the output is the result of voting among the three copies of the program. If one instance of the application disagrees with the other two, it is killed, since there was likely a collision between heap objects in that one. Similarly, if one instance dies with a segfault or other error, the others remain running.

Surviving copies can be forked to replace copies which were killed off, though this reduces the independence among copies.

Posted Date: 3/13/2013 2:49:51 AM | Location : United States







Related Discussions:- Diehard allocator - custom allocators, Assignment Help, Ask Question on Diehard allocator - custom allocators, Get Answer, Expert's Help, Diehard allocator - custom allocators Discussions

Write discussion on Diehard allocator - custom allocators
Your posts are moderated
Related Questions
Define a state which is not a fundamental process state Answer: Blocked state is not a fundamental process state

Deadlock Avoidance It's a method to evade deadlock by careful resource scheduling. This approach to the deadlock problem foresees deadlock before it actually occurs. This a

Calculate the Average Waiting Time CPU burst time points out the time, the process needs the CPU. The subsequent are the set of processes with their respective CPU burst time (

MEMORY MANAGEMENT USING BUDDY SUSTEM Here we are dividing the memory as powers of two as well as we are selecting the space which is smallest but large enough to hold a process

function of lazy swapper

Facilities of a Debug Monitor Facilities of a debug monitor are like this: Setting breakpoints in the program Initiating a debug conversation while control reaches

Android operating system is an open source, Linux-based Smartphone OS. It is the world's most popular mobile platform with more than 700,000 applications and 25 billion downlo

What is real time system? A real time system has well explained, fixed time constraints. Processing must be done within the explained constraints, or the system will fail. It i

Note that the parameter for scanf doesn't need the address operators & because name is an address. However the variable name has no defined space. This can cause problems within C

Q. List the four steps that are essential to run a program on a completely dedicated machine. Answer: a) Reserve machine time b) Manually load program into memory c)