computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and development of both hardware and software. Computing has scientific, ...

a storage violation is a hardware or software fault that occurs when a task attempts to access an area of

computer storage Computer data storage is a technology consisting of computer components and recording media that are used to retain digital data. It is a core function and fundamental component of computers. The central processing unit (CPU) of a compute ...

which it is not permitted to access.

Types of storage violation

Storage violation can, for instance, consist of reading from, writing to, or freeing storage not owned by the task. A common type of storage violation is known as a stack buffer overflow where a program attempts to exceed the limits set for its

call stack In computer science, a call stack is a stack data structure that stores information about the active subroutines of a computer program. This kind of stack is also known as an execution stack, program stack, control stack, run-time stack, or mac ...

. It can also refer to attempted modification of memory "owned" by another thread where there is incomplete (or no) memory protection.

Avoidance of storage violations

Storage violations can occur in transaction systems such as CICS in circumstances where it is possible to write to storage not owned by the transaction; such violations can be reduced by enabling features such as storage protection and transaction isolation.

Detection of storage violations

Storage violations can be difficult to detect as a program can often run for a period of time after the violation before it crashes. For example, a pointer to a freed area of memory can be retained and later reused causing an error. As a result, efforts focus on detecting violations as they occur, rather than later when the problem is observed. In systems such as CICS, storage violations are sometimes detected (by the CICS kernel) by the use of "signatures", which can be tested to see if they have been overlaid. An alternative runtime library may be used to better detect storage violations, at the cost of additional overhead. Some programming languages use software

bounds checking In computer programming, bounds checking is any method of detecting whether a variable is within some bounds before it is used. It is usually used to ensure that a number fits into a given type (range checking), or that a variable being used as ...

to prevent these occurrences. Some program

debugging In computer programming and software development, debugging is the process of finding and resolving '' bugs'' (defects or problems that prevent correct operation) within computer programs, software, or systems. Debugging tactics can involve i ...

software will also detect violations during testing.

Common causes

*A runaway subscript leading to illegal use of reference modification during run time. *Linkage layout mismatch between called and the calling elements. *Use of previously freed (and sometimes already re-allocated) memory.

Examples of software detecting storage violations

* Intertest originally from Online Software International, later Computer Associates

References

*
CICS problem determination Guide

External links

*https://plus.google.com/u/1/collection/wUwasB Marketing material for other product detecting storage violations Computer memory Memory management {{compsci-stub