QA·C Help - 2811

	2811	Definite: Dereference of NULL pointer.

NULL pointers

A definite anomaly has been detected. Examination of the context indicates that this expression will always result in the dereferencing of a null pointer. The result of any attempt to dereference a null pointer value is undefined.

In the example below, p is NULL throughout the code contained in the "if" block and the result of the dereferencing operation will always be undefined.


/*PRQA S 504,2017,2983,2986,3199,3203,3227,3408,3412,3673,4600 ++*/
#define NULL (void *)0

void foo(int *p)
{
    int r;

    if (p == NULL)
    {
        r = *p;             /* 2811 */
    }
}

MISRA-C:2004 Rules applicable to message 2811:

Rule 20.3 (Required)	The validity of values passed to library functions shall be checked.
Rule 21.1 (Required)	Minimisation of run-time failures shall be ensured by the use of at least one of (a) static analysis tools/techniques; (b) dynamic analysis tools/techniques; (c) explicit coding of checks to handle run-time faults

See also:

2810 Constant: Dereference of NULL pointer.
2812 Apparent: Dereference of NULL pointer.
2813 Suspicious: 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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MISRA-C:2004 Compliance Module 3.2
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