CWE-188: Reliance on Data/Memory Layout
Description
The product makes invalid assumptions about how protocol data or memory is organized at a lower level, resulting in unintended program behavior.
Submission Date :
July 19, 2006, midnight
Modification Date :
2023-06-29 00:00:00+00:00
Organization :
MITRE
Extended Description
When changing platforms or protocol versions, in-memory organization of data may change in unintended ways. For example, some architectures may place local variables A and B right next to each other with A on top; some may place them next to each other with B on top; and others may add some padding to each. The padding size may vary to ensure that each variable is aligned to a proper word size.
In protocol implementations, it is common to calculate an offset relative to another field to pick out a specific piece of data. Exceptional conditions, often involving new protocol versions, may add corner cases that change the data layout in an unusual way. The result can be that an implementation accesses an unintended field in the packet, treating data of one type as data of another type.
Example - 1
In this example function, the memory address of variable b is derived by adding 1 to the address of variable a. This derived address is then used to assign the value 0 to b.
char a;char b;*(&a + 1) = 0;void example() {}Here, b may not be one byte past a. It may be one byte in front of a. Or, they may have three bytes between them because they are aligned on 32-bit boundaries.
Related Weaknesses
This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined to give an overview of the different insight to similar items that may exist at higher and lower levels of abstraction.
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