CWE-464 Addition of Data Structure Sentinel

The accidental addition of a data-structure sentinel can cause serious programming logic problems.

Data-structure sentinels are often used to mark the structure of data. A common example of this is the null character at the end of strings or a special sentinel to mark the end of a linked list. It is dangerous to allow this type of control data to be easily accessible. Therefore, it is important to protect from the addition or modification of sentinels.

• Integrity: Modify Application Data — Generally this error will cause the data structure to not work properly by truncating the data.

• [Implementation, Architecture and Design] Encapsulate the user from interacting with data sentinels. Validate user input to verify that sentinels are not present. • [Implementation] Proper error checking can reduce the risk of inadvertently introducing sentinel values into data. For example, if a parsing function fails or encounters an error, it might return a value that is the same as the sentinel. • [Architecture and Design] Use an abstraction library to abstract away risky APIs. This is not a complete solution. • [Operation] Use OS-level preventative functionality. This is not a complete solution.