V3106. Possibly index is out of bound.


When indexing into a variable of type 'array', 'list', or 'string', an 'IndexOutOfRangeException' exception may be thrown if the index value is outbound the valid range. The analyzer can detect some of such errors.

For example, it may happen when iterating through an array in a loop:

int[] buff = new int[25];
for (int i = 0; i <= 25; i++)
  buff[i] = 10;

Keep in mind that the first item's index is 0 and the last item's index is the array size minus one. Fixed code:

int[] buff = new int[25];
for (int i = 0; i < 25; i++)
  buff[i] = 10;

Errors like that are found not only in loops but in conditions with incorrect index checks as well:

void ProcessOperandTypes(ushort opCodeValue, byte operandType)
{
  var OneByteOperandTypes = new byte[0xff];
  if (opCodeValue < 0x100)
  {
    OneByteOperandTypes[opCodeValue] = operandType;
  }
  ...
}

Fixed version:

void ProcessOperandTypes(ushort opCodeValue, byte operandType)
{
  var OneByteOperandTypes = new byte[0xff];
  if (value < 0xff)
  {
    OneByteOperandTypes[value] = operandType;
  }
  ...
}

Programmers also make mistakes of this type when accessing a particular item of an array or list.

void Initialize(List<string> config)
{
  ...
  if (config.Count == 16)
  {
    var result = new Dictionary<string, string>();
    result.Add("Base State", config[0]);
    ...
    result.Add("Sorted Descending Header Style", config[16]);
  }
  ...
}

In this example, the programmer made a mistake in the number of entries in the 'config' list. The fixed version should look like this:

void Initialize(List<string> config)
{
  ...
  if (config.Count == 17)
  {
    var result = new Dictionary<string, string>();
    result.Add("Base State", config[0]);
    ...
    result.Add("Sorted Descending Header Style", config[16]);
  }
  ...
}

According to Common Weakness Enumeration, potential errors found by using this diagnostic are classified as CWE-125, CWE-787.

You can look at examples of errors detected by the V3106 diagnostic.


Bugs Found

Checked Projects
367
Collected Errors
13 552