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
Explain the different sections of a process.     Entry section     Critical section     Exit section     Remainder section Consider a system inclusive of n processe

i need to complete project on lan architceture RAIDs etc

Q. Catalogue the design goals of Windows XP. Answer: Design goals comprise security and reliability and Windows and POSIX application compatibility with high performance and ex

In a  p system each part (RAM, ROM, I/O) has a unique set of numbers. The allocation of these numbers is usually stated in the form of a memory map. This is a plot of data bus agai

A file system depends on data structures about the files, beside the file structure. The former is named metadata-data that defines data. Each file is accumulated with an inode, wh

What is linked allocation, as detailed in text? Directory has pointers to first and last blocks of file. Every block of file (except last) has pointer to the next block.

Sharing segments between processes without requiring the same segment number is possible in a dynamically linked segmentation system. a. Define a system that permits sta

The swapper work s on the biggest scheduling priority. Initially it will look for any sleeping process, if not get then it will see for the ready-to-run process for swapping. Bu

A scheduler that selects processes from secondary storage device is known as                    Medium term scheduler is a scheduler that selects processes from secondary stor

Explain the Advantage of Assembly Language The advantages of assembly language program is: a)    Reduced errors  b)    Faster translation times  c)    Changes could be ma