Memory Dump Analysis Anthology, Volume 12 by Software Diagnostics Institute & Dmitry Vostokov

Author:Software Diagnostics Institute & Dmitry Vostokov [Software Diagnostics Institute]
Language: eng
Format: epub
Publisher: OpenTask
Published: 2019-12-03T16:00:00+00:00

Analysis Pattern Duality

Some of our memory analysis patterns are parameterized by structural constraints (such as a particular type of space or dump, or a memory region) or objects (for example, synchronization). We recently worked on a few analysis patterns and discovered the type of duality between them when the parameter itself could have related problems:

ProblemPattern(Parameter) <-> ParameterProblem(ProblemPattern)

For example, Insufficient Memory (Stack, Volume 11) vs. Stack Overflow (Insufficient Memory). In the first analysis pattern variant, insufficient memory may be reported because of the full stack region, and in the second analysis pattern variant, stack overflow is reported because there is not enough memory to expand stack region.

This duality can aid in new pattern discoveries and especially in analyzing possible root causes and their causal mechanisms (software pathology) given the multiplicity of diagnostic indicators when we consider parameters as analysis patterns themselves. Let’s look at another example: Invalid Pointer (Insufficient Memory). It is a common sequence when a memory leak fails memory allocation, and then certain pointers remain uninitialized or NULL. Consider its dual Insufficient Memory (Invalid Pointer) when, for example, memory is not released because some pointer becomes invalid. The latter can happen when memory is overwritten with NULL values, or access violation is handled and ignored.

The closest mathematical analogy here is order duality43. It is different from the duality of software artifacts (De Broglie Trace Duality, Volume 10), such as logs and memory dumps, and memory space dualities (Dual Stack Trace, Volume 6).

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