CWE-252 Unchecked Return Value

The product does not check the return value from a method or function.

• Availability, Integrity: Unexpected State, Varies by Context, DoS: Crash, Exit, or Restart — The product could be prevented from detecting unexpected states and conditions, placing the product into a state that could lead to a crash or other unintended behaviors. • Access Control: Bypass Protection Mechanism — If the method/function is used for a protection mechanism, then an unchecked return value could prevent the code from being able to see if the protection mechanism fails. For example, if the program calls a function to drop privileges but does not check the return code to ensure that privileges were successfully dropped, then the program will continue to operate with the higher privileges.

• [Implementation] Check the results of all functions that return a value and verify that the value is expected. • [Implementation] For any pointers that could have been modified or provided from a function that can return NULL, check the pointer for NULL before use. When working with a multithreaded or otherwise asynchronous environment, ensure that proper locking APIs are used to lock before the check, and unlock when it has finished [REF-1484]. • [Implementation] Ensure that you account for all possible return values from the function. • [Implementation] When designing a function, make sure you return a value or throw an exception in case of an error.

• Automated Static Analysis: Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)

• CVE-2020-17533: Chain: unchecked return value (CWE-252) of some functions for policy enforcement leads to authorization bypass (CWE-862) • CVE-2020-6078: Chain: The return value of a function returning a pointer is not checked for success (CWE-252) resulting in the later use of an uninitialized variable (CWE-456) and a null pointer dereference (CWE-476) • CVE-2019-15900: Chain: sscanf() call is used to check if a username and group exists, but the return value of sscanf() call is not checked (CWE-252), causing an uninitialized variable to be checked (CWE-457), returning success to allow authorization bypass for executing a privileged (CWE-863). • CVE-2007-3798: Unchecked return value leads to resultant integer overflow and code execution. • CVE-2006-4447: Program does not check return value when invoking functions to drop privileges, which could leave users with higher privileges than expected by forcing those functions to fail. • CVE-2006-2916: Program does not check return value when invoking functions to drop privileges, which could leave users with higher privileges than expected by forcing those functions to fail. • CVE-2008-5183: Chain: unchecked return value can lead to NULL dereference • CVE-2010-0211: Chain: unchecked return value (CWE-252) leads to free of invalid, uninitialized pointer (CWE-824). • CVE-2017-6964: Linux-based device mapper encryption program does not check the return value of setuid and setgid allowing attackers to execute code with unintended privileges. • CVE-2002-1372: Chain: Return values of file/socket operations are not checked (CWE-252), allowing resultant consumption of file descriptors (CWE-772).