Mismatched allocation and deallocation

Description

Using a deallocation function that does not match the allocator can cause a vulnerability. Examples include releasing an array allocated with new[] using delete, or releasing a kernel pool allocation with ordinary free.

Potential impact

• Corrupted heap or pool metadata can cause crashes.
• Destructors may not run correctly, causing resource leaks or undefined behavior.

Remediation

1. Release malloc-family allocations with free.
2. Pair new with delete, and new[] with delete[].
3. Use the matching release API for platform-specific or kernel allocations.

Examples

Before

void run() {
    int *items = new int[16];
    delete items;
}

After

void run() {
    int *items = new int[16];
    delete[] items;
}

Explanation:

• Before: delete does not match the array allocation.
• After: delete[] matches the allocation made with new[].

References

• CWE-762