[previous] 2842 [next] Apparent: Dereference of an invalid pointer value.
Arrays

An apparent anomaly has been detected. Preceding operations imply that this expression will sometimes result in an access outside the bounds of an array.

For example, in the code shown below, out of bounds array access will occur if the index n is greater than or equal to 10 - the presence of the "if" statement suggests that this is likely. Of course, if the value of n passed to function foo is always less than 10, the upper bound of the array will not be exceeded; but this would imply that the "if" statement is redundant and any code contained in the "if" block is also redundant.


/*PRQA S 2017,3120,3132,3203,3227,3408,3605,3689 ++*/
void foo(int n)
{
    int a[10];

    if (n > 10)
    {
    }

    a[n] = 1;                   /* 2842 */
}

MISRA-C:2004 Rules applicable to message 2842:

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:

QA·C Source Code Analyser 8.1
MISRA-C:2004 Compliance Module 3.2
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