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If control reaches the closing curly brace (}) of a non-void function without evaluating a return statement, using the return value of the function call is undefined behavior. (See undefined behavior 8886.)

Noncompliant Code Example

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MSC37-C-EX1: According to the C Standard, 5.1.2.23.34, paragraph 1 [ISO/IEC 9899:20112024], "Reaching the } that terminates the main function returns a value of 0." As a result, it is permissible for control to reach the end of the main() function without executing a return statement.

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Using the return value from a non-void function where control reaches the end of the function without evaluating a return statement can lead to buffer overflow vulnerabilities as well as other unexpected program behaviors.

Related Vulnerabilities

Search for vulnerabilities resulting from the violation of this rule on the CERT website.

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Bibliography

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