Zennoxa Shield
Rules / Rust
SHIELD-RUST-014

Potential integer overflow in allocation size

lowRustCWE-190CVSS 4

What it detects

with_capacity/Vec sizing from a multiplication of untrusted values can overflow.

How to fix

Use checked_mul and validate sizes before allocating from untrusted input.

Vulnerable — Shield flags thismatrix.rs
pub fn alloc_matrix(rows: usize, cols: usize) -> Vec<f64> {
    // rows and cols are read from the file header.
    let mut cells = Vec::with_capacity(rows * cols);
    cells.resize(rows * cols, 0.0);
    cells
}
Fixed — scans cleanmatrix.rs
const MAX_CELLS: usize = 1_000_000;

pub fn alloc_matrix(rows: usize, cols: usize) -> Option<Vec<f64>> {
    let len = rows.checked_mul(cols)?;
    if len > MAX_CELLS {
        return None;
    }
    let mut cells = Vec::with_capacity(len);
    cells.resize(len, 0.0);
    Some(cells)
}

Both snippets are verified against the shipped scanner: the vulnerable one triggers SHIELD-RUST-014, the fixed one does not.

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SHIELD-RUST-014: Potential integer overflow in allocation size — Zennoxa Shield