CERT.FILE_PTR.DEREF.RETURN

A pointer to a FILE object (returned by function) shall not be dereferenced.

Vulnerability and risk

Dereferencing the pointer to a FILE object that is returned by a function may result in unexpected behavior.

Vulnerable code example

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   #include <cstring>
  
   typedef struct __sFILE {
       int pos;
   } FILE;
  
   FILE *getFile() {
       FILE *p;
       return p;
  }
  
  static int i = 1;
  int *getInt() {
      return &i;
  }
  
  void func9_function_return ( void )
  {
      int x = getFile()->pos;           
      FILE file1 = *getFile();          
      char chr = *((char*)getFile());   
  }

In this noncompliant example, Klocwork reports a defect CERT.FILE_PTR.DEREF.RETURN on lines 19, 20, and 21 because dereferencing a pointer to a FILE object that is returned by a function may result in unexpected behaviour.

Fixed code example

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#include <cstring>

typedef struct __sFILE {
    int pos;
} FILE;

FILE *getFile() {
    FILE *p;
    return p;
}

static int i = 1;
int *getInt() {
    return &i;
}

void func9_function_return ( void )
{
       FILE file2 = *((FILE*)getInt());           
}

The above example is compliant because no code dereferences a pointer to a FILE object that is returned by a function.

Related checkers

• MISRA.FILE_PTR.DEREF.RETURN.2012

External guidance

• CERT FIO38-C: Do not copy a FILE object