Excessive memory allocation from user input

Excessive memory allocation from user input

Description

Using an unvalidated input size with make, bytes.Repeat, or strings.Repeat can allocate excessive memory.

Potential impact

Memory exhaustion or runtime panics may deny service.
A small request may trigger large resource consumption.

Remediation

Check that the size parses successfully and is between zero and the allowed maximum before allocating.
Set separate limits for request bodies, uploads, and repetition counts.

Examples

Before

go

size, _ := strconv.Atoi(r.FormValue("n"))
buf := make([]byte, size)

After

go

size, err := strconv.Atoi(r.FormValue("n"))
if err != nil || size < 0 || size > 4096 {
    return nil
}
buf := make([]byte, size)

Explanation:

Before: An attacker can supply a large size to make or a repetition-based allocation API and exhaust memory.
After: Reject invalid or out-of-range sizes before allocation.

References

CWE-770