The product does not properly check when a function or operation returns a value that is legitimate for the function, but is not expected by the product.
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-2004-1395Certain packets (zero byte and other lengths) cause a recvfrom call to produce an unexpected return code that causes a server's listening loop to exit.
CVE-2002-2124Unchecked return code from recv() leads to infinite loop.
CVE-2005-2553Kernel function does not properly handle when a null is returned by a function call, causing it to call another function that it shouldn't.
CVE-2005-1858Memory not properly cleared when read() function call returns fewer bytes than expected.
CVE-2000-0536Bypass access restrictions when connecting from IP whose DNS reverse lookup does not return a hostname.