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The exact treatment of error conditions from math functions is quite complicated.  C99 Section 7.12.1 defines the following behavior for floating point overflow \[[ISO/IEC 9899:1999|AA. Bibliography#ISO/IEC 9899-1999]\]:

A floating result overflows if the magnitude of the mathematical result is finite but so large that the mathematical result cannot be represented without extraordinary roundoff error in an object of the specified type. If a floating result overflows and default rounding is in effect, or if the mathematical result is an exact infinity from finite arguments (for example log(0.0)), then the function returns the value of the macro HUGE_VAL, HUGE_VALF, or HUGE_VALL according to the return type, with the same sign as the correct value of the function; if the integer expression math_errhandling & MATH_ERRNO is nonzero, the integer expression errno acquires the value ERANGE; if the integer expression math_errhandling & MATH_ERREXCEPT is nonzero, the ''divide-by-zero'' floating-point exception is raised if the mathematical result is an exact infinity and the ''overflow'' floating-point exception is raised otherwise.

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It is also difficult to check for math errors using {{errno}} because an implementation might not set it. For real functions, the programmer can tell whether the implementation sets {{errno}} by checking whether {{math_errhandling & MATH_ERRNO}} is nonzero. For complex functions, the C99, Section 7.3.2, simply states "an implementation may set {{errno}} but is not required to" \[[ISO/IEC 9899:1999|AA. Bibliography#ISO/IEC 9899-1999]\].

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#include <math.h>
#if defined(math_errhandling) \
  && (math_errhandling & MATH_ERREXCEPT)
#include <fenv.h>
#endif

/* ... */

#if defined(math_errhandling) \
  && (math_errhandling & MATH_ERREXCEPT)
  feclearexcept(FE_ALL_EXCEPT);
#endif
errno = 0;

/* call the function */

#if !defined(math_errhandling) \
  || (math_errhandling & MATH_ERRNO)
if (errno != 0) {
  /* handle range error */
}
#endif
#if defined(math_errhandling) \
  && (math_errhandling & MATH_ERREXCEPT)
if (fetestexcept(FE_INVALID
               | FE_DIVBYZERO
               | FE_OVERFLOW
               | FE_UNDERFLOW) != 0) {
  /* handle range error */
}
#endif

See guideline FLP03-C. Detect and handle floating point errors for more details on how to detect floating point errors.

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The following noncompliant code determines the square root of x.

double x;
double result;

result = sqrt(x);

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Automated Detection

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Related Vulnerabilities

Search for vulnerabilities resulting from the violation of this rule on the CERT website.

Other Languages

Related Guidelines

This rule appears in the C++ Secure Coding Standard as : FLP32-CPP. Prevent or detect domain and range errors in math functions.

Bibliography

\[[ISO/IEC 9899:1999|AA. Bibliography#ISO/IEC 9899-1999]\] Section 7.3, "Complex arithmetic <{{complex.h}}>", and Section 7.12, "Mathematics <{{math.h}}>"
\[[MITRE 072007|AA. Bibliography#MITRE 07]\] [CWE ID 682|http://cwe.mitre.org/data/definitions/682.html], "Incorrect Calculation"
\[[Plum 851985|AA. Bibliography#Plum 85]\] Rule 2-2
\[[Plum 891989|AA. Bibliography#Plum 91]\] Topic 2.10, "conv - conversions and overflow"

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