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IAR Embedded Workbench for RISC-V 3.40

ARR-neg-index

In this section:
Synopsis

An array is accessed with a negative subscript value.

Enabled by default

Yes

Severity/Certainty

High/High

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Full description

An array is accessed with a negative subscript value, causing an illegal memory access. This might corrupt data and/or crash the application, and result in security vulnerabilities. This check is identical to CERT-ARR30-C_e.

Coding standards
CERT ARR30-C

Do not form or use out of bounds pointers or array subscripts

CWE 120

Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

CWE 124

Buffer Underwrite ('Buffer Underflow')

CWE 127

Buffer Under-read

Code examples

The following code example fails the check and will give a warning:

void foo(int n)
{
  int x[n];
  int i = 0;
  if (i == 0)
    i--;
  x[i] = 5; //i is -1 at this point
}

The following code example passes the check and will not give a warning about this issue:

void foo(int n)
{
  int x[n];
  int i = 5;
  if (i == 0)
    i--;
  x[i] = 5;  //OK, since i is 4
}