Integer Overflow in Buffalo with Cockroachdb

Integer overflow in a Buffalo application using CockroachDB can occur when arithmetic on integer values exceeds the fixed size of the type, wrapping to a lower value and producing an unexpected result that may bypass length or capacity checks. In Buffalo, this commonly arises when computing sizes for allocations, buffer lengths, or pagination limits before values are sent to CockroachDB.

When an attacker can influence the integers involved—such as a page size, batch count, or loop bound—and the application performs unchecked arithmetic, overflow can cause the computed value to become small (e.g., wrapping to zero or a very small number). If the result is used to allocate a buffer, slice, or to construct SQL pagination, it may lead to out-of-bounds reads, excessive resource consumption, or data exposure.

CockroachDB, while PostgreSQL-wire compatible and strict in many numeric behaviors, does not inherently prevent overflow introduced by the application layer. For example, if Buffalo computes a LIMIT value using unchecked arithmetic and passes it to a CockroachDB query, an overflowed LIMIT might produce an unexpectedly large or small result set. This can interact with other checks such as Input Validation and BFLA/Privilege Escalation if the overflow enables privilege-related bypasses or data exposure.

Consider a scenario where Buffalo calculates a total buffer size as pageSize * numPages before issuing a CockroachDB query. If both values are user-supplied integers and the multiplication overflows, the actual allocated buffer may be much smaller than intended, leading to memory corruption risks when handling query results. Even though CockroachDB safely stores the data, the application logic around pagination and slicing becomes unsafe due to the overflow.

To detect such issues, middleBrick scans unauthenticated endpoints that use CockroachDB-backed Buffalo services, checking for missing bounds checks on integer inputs, unsafe arithmetic, and improper use of pagination parameters. Findings include severity, context, and remediation guidance mapped to OWASP API Top 10 and related compliance frameworks.

Remediation centers on validating and sanitizing integer inputs before arithmetic and before constructing CockroachDB queries. Use checked arithmetic or bounded integer types, enforce server-side limits, and avoid relying on wrapped values for security-sensitive operations such as pagination or buffer sizing.

Below are concrete examples for a Buffalo service that interacts with CockroachDB using pgx. The examples demonstrate safe pagination and safe arithmetic before query construction.

// Safe pagination in Buffalo with CockroachDB using pgx
package controllers

import (
    "context"
    "github.com/gobuffalo/buffalo"
    "github.com/jackc/pgx/v5"
    "net/http"
    "strconv"
)

func UsersList(c buffalo.Context) error {
    db, _ := c.Value("db").(*pgx.Conn) // assume connection injected
    pageStr := c.Param("page")
    sizeStr := c.Param("size")

    page, err := strconv.Atoi(pageStr)
    if err != nil || page < 1 {
        return c.Render(http.StatusBadRequest, r.JSON(map[string]string{"error": "invalid page"}))
    }
    size, err := strconv.Atoi(sizeStr)
    if err != nil || size < 1 || size > 1000 {
        return c.Render(http.StatusBadRequest, r.JSON(map[string]string{"error": "invalid size"}))
    }

    // Use checked arithmetic: compute offset with validation
    offset := (page - 1) * size
    // Ensure offset does not overflow int; in Go, int is architecture-dependent but values are bounded by DB limits
    if offset < 0 {
        return c.Render(http.StatusBadRequest, r.JSON(map[string]string{"error": "offset overflow"}))
    }

    rows, err := db.Query(context.Background(),
        "SELECT id, name FROM users ORDER BY id LIMIT $1 OFFSET $2",
        pgx.Value(size), pgx.Value(offset))
    if err != nil {
        return c.Render(http.StatusInternalServerError, r.JSON(map[string]string{"error": "db error"}))
    }
    defer rows.Close()
    // process rows...
    return c.Render(http.StatusOK, r.JSON(rows))
}

In this code:

• Input validation ensures page and size are positive integers and size is capped at a safe maximum (e.g., 1000).
• Offset calculation is guarded against negative results which can indicate wrap-around on underflow scenarios in certain contexts; in Go, integer overflow on signed ints is undefined behavior, so preventing large inputs avoids it.
• The query uses CockroachDB-compatible placeholders with pgx, ensuring safe parameter handling and avoiding injection even if values were manipulated.

For arithmetic that must aggregate values (e.g., total items or batch sizes), use explicit checks or types with defined overflow behavior:

// Checked multiplication to avoid overflow in Buffalo before CockroachDB usage
func safeMultiply(a, b int) (int, error) {
    if a == 0 || b == 0 {
        return 0, nil
    }
    result := a * b
    if a != 0 && result/a != b {
        return 0, fmt.Errorf("integer overflow")
    }
    return result, nil
}

// Usage in a handler
product, err := safeMultiply(page, size)
if err != nil || product > 1000000 { // enforce a global cap
    return c.Render(http.StatusBadRequest, r.JSON(map[string]string{"error": "invalid aggregation"}))
}

These patterns ensure that values sent to CockroachDB remain within expected bounds, preventing unexpected behavior due to integer overflow in the Buffalo layer.