Incorrect Check of Function Return Value

The software incorrectly checks a return value from a function, which prevents the software from detecting errors or exceptional conditions.


Important and common functions will return some value about the success of its actions. This will alert the program whether or not to handle any errors caused by that function.


The following examples help to illustrate the nature of this weakness and describe methods or techniques which can be used to mitigate the risk.

Note that the examples here are by no means exhaustive and any given weakness may have many subtle varieties, each of which may require different detection methods or runtime controls.

Example One

This code attempts to allocate memory for 4 integers and checks if the allocation succeeds.

tmp = malloc(sizeof(int) * 4);
if (tmp < 0 ) {

  //should have checked if the call returned 0


The code assumes that only a negative return value would indicate an error, but malloc() may return a null pointer when there is an error. The value of tmp could then be equal to 0, and the error would be missed.

See Also

SEI CERT C Coding Standard - Guidelines 50. POSIX (POS)

Weaknesses in this category are related to the rules and recommendations in the POSIX (POS) section of the SEI CERT C Coding Standard.

SEI CERT C Coding Standard - Guidelines 12. Error Handling (ERR)

Weaknesses in this category are related to the rules and recommendations in the Error Handling (ERR) section of the SEI CERT C Coding Standard.

SFP Secondary Cluster: Unchecked Status Condition

This category identifies Software Fault Patterns (SFPs) within the Unchecked Status Condition cluster (SFP4).

Comprehensive CWE Dictionary

This view (slice) covers all the elements in CWE.

CWE Cross-section

This view contains a selection of weaknesses that represent the variety of weaknesses that are captured in CWE, at a level of abstraction that is likely to be useful t...

Weaknesses Introduced During Implementation

This view (slice) lists weaknesses that can be introduced during implementation.

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