CWE-464

Extended description

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.

Common consequences1

• IntegrityModify Application Data

  Generally this error will cause the data structure to not work properly by truncating the data.

Potential mitigations4

1. ImplementationArchitecture and Design

   Encapsulate the user from interacting with data sentinels. Validate user input to verify that sentinels are not present.

2. 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.

3. Architecture and Design

   Use an abstraction library to abstract away risky APIs. This is not a complete solution.

4. Operation

   Use OS-level preventative functionality. This is not a complete solution.

Relationships1

• ChildOfCWE-138