Return of Stack Variable Address

A function returns the address of a stack variable, which will cause unintended program behavior, typically in the form of a crash.


Because local variables are allocated on the stack, when a program returns a pointer to a local variable, it is returning a stack address. A subsequent function call is likely to re-use this same stack address, thereby overwriting the value of the pointer, which no longer corresponds to the same variable since a function's stack frame is invalidated when it returns. At best this will cause the value of the pointer to change unexpectedly. In many cases it causes the program to crash the next time the pointer is dereferenced.


The following examples help to illustrate the nature of this weakness and describe methods or techniques which can be used to mitigate the risk.

Note that the examples here are by no means exhaustive and any given weakness may have many subtle varieties, each of which may require different detection methods or runtime controls.

Example One

The following function returns a stack address.

char* getName() {
  char name[STR_MAX];
  return name;

See Also

CISQ Quality Measures - Reliability

Weaknesses in this category are related to the CISQ Quality Measures for Reliability. Presence of these weaknesses could reduce the reliability of the software.

SEI CERT C Coding Standard - Guidelines 02. Declarations and Initialization (DCL)

Weaknesses in this category are related to the rules and recommendations in the Declarations and Initialization (DCL) section of the SEI CERT C Coding Standard.

Bad Coding Practices

Weaknesses in this category are related to coding practices that are deemed unsafe and increase the chances that an exploitable vulnerability will be present in the ap...

Comprehensive CWE Dictionary

This view (slice) covers all the elements in CWE.

CISQ Data Protection Measures

This view outlines the SMM representation of the Automated Source Code Data Protection Measurement specifications, as identified by the Consortium for Information & So...

Quality Weaknesses with Indirect Security Impacts

CWE identifiers in this view (slice) are quality issues that only indirectly make it easier to introduce a vulnerability and/or make the vulnerability more difficult t...

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