QA·C Help - 2813

	2813	Suspicious: Dereference of NULL pointer.

NULL pointers

Dataflow analysis has identified a code construct which is suspicious. The code may be entirely safe but further investigation is advisable.

A pointer value is being dereferenced and examination of the immediate context suggests that the pointer value could sometimes be NULL.

The result of any attempt to dereference a null pointer value is undefined.

For example, in the code shown below, the pointer 'p' being dereferenced in the 'return' statement, will be NULL unless the parameter 'n' is greater than 0.


/*PRQA S 505,2017,2986,3132,3199,3203,3227,3408,3412,3447,3673,4600 ++*/
#define NULL (void *)0

extern int ar[100];

extern int foo(int n)
{
    int  i;
    int *p = NULL;
    
    for (i = 0; i < n; ++i)
    {
        p = &ar[i];
    }

    return *p;                    /* 2813 */
}

See also:

2810 Constant: Dereference of NULL pointer.
2811 Definite: Dereference of NULL pointer.
2812 Apparent: Dereference of NULL pointer.
2814 Possible: Dereference of NULL pointer.
2820 Constant: Arithmetic operation on NULL pointer.
2821 Definite: Arithmetic operation on NULL pointer.
2822 Apparent: Arithmetic operation on NULL pointer.
2823 Suspicious: Arithmetic operation on NULL pointer.
2824 Possible: Arithmetic operation on NULL pointer.

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