Fix unsafe integer conversion in instance_utils.go

[cheyang]

File: pkg/reconciler/instance/utils/instance_utils.go
Line: 145
Rule: go/incorrect-integer-conversion
Severity: High

Issue

The current implementation converts a string to int (architecture-dependent size) and then downcasts to int32 without bounds checking:

list := strings.Split(pod.Name, "-")
componentId = list[len(list)-1]
id, _ := strconv.Atoi(componentId)  //  ❌ Unsafe conversion
return int32(id)

If the integer parsed from the pod name exceeds math.MaxInt32 (2147483647) or is below math.MinInt32 (-2147483648), the conversion to int32 will silently wrap, causing undefined behavior (e.g., negative IDs, overflow bugs).

Recommended Fix

Replace strconv.Atoi with explicit bounds checking or use strconv.ParseInt with a 32-bit size:

Option 1 (ParseInt with bitSize=32):

idStr := list[len(list)-1]
id, err := strconv.ParseInt(idStr, 10, 32)  // ✅ Automatically enforces 32-bit bounds
if err != nil {
    return 0 // or handle error appropriately
}
return int32(id)

Option 2 (Atoi + Manual Bounds Check):

idStr := list[len(list)-1]
id, err := strconv.Atoi(idStr)
if err != nil {
    return 0 
}
// Explicit bounds check
if id < math.MinInt32 || id > math.MaxInt32 {
    return 0 // or handle overflow
}
return int32(id)

Why This Matters

• Security Impact: Unchecked conversions enable integer overflow exploits (e.g., resource exhaustion, bypassing checks).
• 📏 Correctness: Values outside int32 range corrupt data silently.
• ⚠️ CodeQL Alert: This violates go/incorrect-integer-conversion (reference: strconv.Atoi → int32).