Uninitialized Memory in Fiber with Cockroachdb

Uninitialized memory in a Fiber application that uses CockroachDB can lead to information disclosure or erratic behavior when sensitive data left over from prior allocations is inadvertently exposed to the database layer. This typically occurs when structures or buffers are declared without explicit initialization and are later used to construct SQL queries, marshal JSON for rows, or bind request payloads before being validated.

In a Fiber app, handlers often bind incoming request bodies into Go structs or maps and then pass those values to CockroachDB via the pgx driver or an ORM. If the struct fields are not explicitly set, fields such as string pointers, byte slices, or integer pointers may hold arbitrary memory contents. When such a struct is marshaled to JSON for a query parameter or request body, or when zero-valued fields are omitted and later interpreted as meaningful by application logic, the uninitialized data can be written into the database or reflected back to clients in responses.

With CockroachDB, this risk is exposed during operations that rely on incomplete structs, such as partial updates, dynamic WHERE clauses, or schema-less JSONB columns. For example, if a handler decodes JSON into a struct and then inserts only non-empty fields into a JSONB column, the uninitialized fields may still be included in the serialized form, leaking stale data. Additionally, using zero-value integers or pointers to conditionally build queries can produce unexpected SQL, potentially exposing sensitive information through error messages or logs stored in CockroachDB’s audit trails.

Consider a handler that decodes a JSON payload into a struct and uses it to filter or insert rows. Without proper initialization, fields like ID pointers or byte buffers may contain residual memory, causing the application to send incorrect filters or store unintended metadata. This becomes particularly dangerous when combined with CockroachDB’s distributed nature, where nodes may serialize and replicate data across regions, increasing the surface for unintended data exposure.

To mitigate, always initialize struct fields before use, explicitly validate and sanitize inputs, and avoid relying on zero values to convey intent. Use explicit defaults, clear pointer checks, and ensure JSON serialization includes only intended fields. Complement these practices with runtime scanning using middleBrick, which can detect uninitialized memory exposure by correlating OpenAPI specs with runtime behavior across the API’s authentication, input validation, and data exposure checks.

Remediation centers on ensuring that all data sent to CockroachDB is explicitly initialized and validated before use. Below are concrete Fiber code examples demonstrating safe patterns.

1. Initialize structs and validate before database insertion

package main

import (
    "github.com/gofiber/fiber/v2"
    "github.com/jackc/pgx/v5/pgxpool"
    "context"
    "encoding/json"
)

type UserInput struct {
    Name  *string `json:"name"`
    Email *string `json:"email"`
    Age   *int    `json:"age"`
}

func main() {
    app := fiber.New()
    pool, _ := pgxpool.New(context.Background(), "postgresql://localhost:26257/defaultdb?sslmode=disable")
    
    app.Post("/users", func(c *fiber.Ctx) error {
        var input UserInput
        if err := c.BodyParser(&input); err != nil {
            return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{"error": "invalid payload"})
        }

        // Explicit initialization with defaults
        name := "unknown"
        if input.Name != nil {
            name = *input.Name
        }
        email := "[email protected]"
        if input.Email != nil {
            email = *input.Email
        }
        age := 0
        if input.Age != nil {
            age = *input.Age
        }

        // Safe insert with initialized values
        _, err := pool.Exec(c.Context(),
            "INSERT INTO users (name, email, age) VALUES ($1, $2, $3)",
            name, email, age)
        if err != nil {
            return c.Status(fiber.StatusInternalServerError).JSON(fiber.Map{"error": err.Error()})
        }
        return c.SendStatus(fiber.StatusCreated)
    })
    _ = app.Listen(":3000")
}

2. Use prepared statements and avoid zero-value pointers in WHERE clauses

package main

import (
    "github.com/gofiber/fiber/v2"
    "github.com/jackc/pgx/v5/pgxpool"
    "context"
    "database/sql"
)

type Filter struct {
    Status *string `json:"status"`
    MinAge *int    `json:"min_age"`
}

func buildQuery(filter Filter) (string, []interface{}) {
    base := "SELECT id, name FROM users WHERE 1=1"
    var args []interface{}
    argIndex := 1

    if filter.Status != nil {
        base += " AND status = $" + string(argIndex +'0')
        args = append(args, *filter.Status)
        argIndex++
    }
    if filter.MinAge != nil {
        base += " AND age >= $" + string(argIndex +'0')
        args = append(args, *filter.MinAge)
    }
    return base, args
}

func main() {
    app := fiber.New()
    pool, _ := pgxpool.New(context.Background(), "postgresql://localhost:26257/defaultdb?sslmode=disable")

    app.Post("/search", func(c *fiber.Ctx) error {
        var filter Filter
        if err := c.BodyParser(&filter); err != nil {
            return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{"error": "invalid filter"})
        }

        query, args := buildQuery(filter)
        rows, err := pool.Query(c.Context(), query, args...)
        if err != nil {
            return c.Status(fiber.StatusInternalServerError).JSON(fiber.Map{"error": err.Error()})
        }
        defer rows.Close()

        var results []map[string]interface{}
        for rows.Next() {
            var id int
            var name string
            if err := rows.Scan(&id, &name); err != nil {
                return c.Status(fiber.StatusInternalServerError).JSON(fiber.Map{"error": err.Error()})
            }
            results = append(results, map[string]interface{}{"id": id, "name": name})
        }
        return c.JSON(results)
    })
    _ = app.Listen(":3000")
}

3. Use JSONB with explicit field setting instead of raw struct marshaling

package main

import (
    "github.com/gofiber/fiber/v2"
    "github.com/jackc/pgx/v5/pgxpool"
    "context"
    "encoding/json"
)

type SafeUser struct {
    Name  string `json:"name"`
    Email string `json:"email"`
    Age   int    json:"age"
}

func main() {
    app := fiber.New()
    pool, _ := pgxpool.New(context.Background(), "postgresql://localhost:26257/defaultdb?sslmode=disable")

    app.Post("/users/jsonb", func(c *fiber.Ctx) error {
        var su SafeUser
        if err := c.BodyParser(&su); err != nil {
            return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{"error": "invalid payload"})
        }

        userJSON, err := json.Marshal(su)
        if err != nil {
            return c.Status(fiber.StatusInternalServerError).JSON(fiber.Map{"error": "serialization error"})
        }

        _, err = pool.Exec(c.Context(),
            "INSERT INTO user_profiles (data) VALUES ($1)",
            userJSON)
        if err != nil {
            return c.Status(fiber.StatusInternalServerError).JSON(fiber.Map{"error": err.Error()})
        }
        return c.SendStatus(fiber.StatusCreated)
    })
    _ = app.Listen(":3000")
}

These patterns ensure that no uninitialized memory reaches CockroachDB, reducing the risk of information leakage or malformed queries. Complement these code-level fixes with runtime security analysis using middleBrick, which checks input validation, data exposure, and encryption across your API surface without requiring agent installation.