Do not call a function with the wrong number or type of arguments.
The C Standard identifies five distinct situations in which undefined behavior (UB) may arise as a result of invoking a function using a declaration that is incompatible with its definition or by supplying incorrect types or numbers of arguments:
A pointer is used to call a function whose type is not compatible with the referenced type (220.127.116.11).
For a call to a function without a function prototype in scope, the number of arguments does not equal the number of parameters (18.104.22.168).
For a call to a function without a function prototype in scope where the function is defined with a function prototype, either the prototype ends with an ellipsis or the types of the arguments after promotion are not compatible with the types of the parameters (22.214.171.124).
|For a call to a function without a function prototype in scope where the function is not defined with a function prototype, the types of the arguments after promotion are not compatible with those of the parameters after promotion (with certain exceptions) (126.96.36.199).|
A function is defined with a type that is not compatible with the type (of the expression) pointed to by the expression that denotes the called function (188.8.131.52).
Functions that are appropriately declared (as in DCL40-C. Do not create incompatible declarations of the same function or object) will typically generate a compiler diagnostic message if they are supplied with the wrong number or types of arguments. However, there are cases in which supplying the incorrect arguments to a function will, at best, generate compiler warnings. Although such warnings should be resolved, they do not prevent program compilation. (See MSC00-C. Compile cleanly at high warning levels.)
Noncompliant Code Example
<tgmath.h> provides type-generic macros for math functions. Although most functions from the
<math.h> header have a complex counterpart in
<complex.h>, several functions do not. Calling any of the following type-generic functions with complex values is undefined behavior.
Functions That Should Not Be Called with Complex Values
This noncompliant code example attempts to take the base-2 logarithm of a complex number, resulting in undefined behavior:
Compliant Solution (Complex Number)
clog2() function is not available for an implementation as an extension, the programmer can take the base-2 logarithm of a complex number, using
log() instead of
log() can be used on complex arguments, as shown in this compliant solution:
Compliant Solution (Real Number)
The programmer can use this compliant solution if the intent is to take the base-2 logarithm of the real part of the complex number:
Noncompliant Code Example
In this noncompliant example, the C standard library function
strchr() is called through the function pointer
fp declared with a prototype with incorrectly typed arguments. According to the C Standard, 184.108.40.206, paragraph 8 [ISO/IEC 9899:2011]
A pointer to a function of one type may be converted to a pointer to a function of another type and back again; the result shall compare equal to the original pointer. If a converted pointer is used to call a function whose type is not compatible with the referenced type, the behavior is undefined.
In this compliant solution, the function pointer
fp, which points to the C standard library function
strchr(), is declared with the correct parameters and is invoked with the correct number and type of arguments:
Noncompliant Code Example
In this noncompliant example, the function
f() is defined to take an argument of type
f() is called from another file with an argument of type
In this compliant solution, the prototype for the function
f() is included in the source file in the scope of where it is called, and the function
f() is correctly called with an argument of type
Noncompliant Code Example (POSIX)
The POSIX function
open() [IEEE Std 1003.1:2013] is a variadic function with the following prototype:
open() function accepts a third argument to determine a newly created file's access mode. If
open() is used to create a new file and the third argument is omitted, the file may be created with unintended access permissions. (See FIO06-C. Create files with appropriate access permissions.)
Technically, it is incorrect to pass a third argument to open() when not creating a new file (that is, with the O_CREAT flag not set).
Compliant Solution (POSIX)
In this compliant solution, a third argument is specified in the call to
Calling a function with incorrect arguments can result in unexpected or unintended program behavior.
|Axivion Bauhaus Suite|
|Array parameter mismatch|
Can detect some violations of this rule. In particular, it ensures that all calls to
MISRA C 2012 Rule 8.2
MISRA C 2012 Rule 17.3
Relies on functions declared with prototypes, allow compiler to check
Can detect violation of this rule when the
|LDRA tool suite|
41 D, 21 S, 98 S, 170 S, 496 S, 576 S
Identifiers shall be given for all of the parameters in a function prototype declaration
|Polyspace Bug Finder|
Rule partially covered.
|1331, 1332, 1333, 3002, 3320, 3335||Partially implemented|
|V540, V541, V549, V575, V632, V639, V666, V671, V742, V743, V764, V1004|
|SonarQube C/C++ Plugin|
|S930||Detects incorrect argument count|
|unclassified ("function type matches")||Partially verified (see one compliant and one non-compliant example).|
Key here (explains table format and definitions)
|CERT C Secure Coding Standard||DCL07-C. Include the appropriate type information in function declarators||Prior to 2018-01-12: CERT: Unspecified Relationship|
|CERT C Secure Coding Standard||MSC00-C. Compile cleanly at high warning levels||Prior to 2018-01-12: CERT: Unspecified Relationship|
|CERT C Secure Coding Standard||FIO06-C. Create files with appropriate access permissions||Prior to 2018-01-12: CERT: Unspecified Relationship|
|ISO/IEC TR 24772:2013||Subprogram Signature Mismatch [OTR]||Prior to 2018-01-12: CERT: Unspecified Relationship|
|ISO/IEC TS 17961||Calling functions with incorrect arguments [argcomp]||Prior to 2018-01-12: CERT: Unspecified Relationship|
|MISRA C:2012||Rule 8.2 (required)||Prior to 2018-01-12: CERT: Unspecified Relationship|
|MISRA C:2012||Rule 17.3 (mandatory)||Prior to 2018-01-12: CERT: Unspecified Relationship|
|CWE 2.11||CWE-628, Function Call with Incorrectly Specified Arguments||2017-07-05: CERT: Rule subset of CWE|
CERT-CWE Mapping Notes
Key here for mapping notes
CWE-685 and EXP37-C
EXP37-C = Union( CWE-685, CWE-686) Intersection( CWE-685, CWE-686) = Ø
CWE-686 and EXP37-C
Intersection( EXP37-C, FIO47-C) =
- Invalid argument types passed to format I/O function
EXP37-C – FIO47-C =
- Invalid argument types passed to non-format I/O function
FIO47-C – EXP37-C =
- Invalid format string, but correctly matches arguments in number and type
EXP37-C = Union( CWE-685, CWE-686)
Intersection( CWE-685, CWE-686) = Ø
CWE-628 and EXP37-C
CWE-628 = Union( EXP37-C, list) where list =
- Improper ordering of function arguments (that does not violate argument types)
- Wrong argument values or references
|[ISO/IEC 9899:2011]||220.127.116.11, "Pointers"|
18.104.22.168, "Function Calls"
|[IEEE Std 1003.1:2013]|
|[Spinellis 2006]||Section 2.6.1, "Incorrect Routine or Arguments"|