Suspicious pointer scaling to void¶

ID: cpp/suspicious-pointer-scaling-void
Kind: problem
Security severity: 8.8
Severity: warning
Precision: medium
Tags:
   - security
   - external/cwe/cwe-468
Query suites:
   - cpp-security-extended.qls
   - cpp-security-and-quality.qls

Click to see the query in the CodeQL repository

Casting arbitrary pointers into void* and then accessing their contents should be done with care. The results may not be portable.

This query finds pointer arithmetic expressions where a pointer to void (or similar) is then cast to another type and dereferenced.

Recommendation¶

Whenever possible, use the array subscript operator rather than pointer arithmetic. For example, replace *(p+k) with p[k].
Cast to the correct type before using pointer arithmetic. For example, if the type of p is void* but it really points to an array of type double[] then use the syntax (double*)p + k to get a pointer to the k’th element of the array.
If pointer arithmetic must be done with a single-byte width, prefer char * to void *, as pointer arithmetic on void * is a nonstandard GNU extension.

Example¶

char example1(int i) {
  int intArray[5]