Buffer Overflow in Chi with Cockroachdb

A buffer overflow in a Chi application that uses CockroachDB typically arises when untrusted input is copied into a fixed-size memory buffer without proper length checks, while database interactions amplify the impact. Chi is a lightweight HTTP router for Go; when handlers parse request parameters, headers, or body into fixed-size buffers (for example, byte arrays or C-style strings via CGO), oversized input can overflow the buffer and corrupt adjacent memory. CockroachDB, a distributed SQL database, comes into play when the application writes or logs data received from such requests into the database. If the application does not validate input length before inserting or upserting rows, a maliciously crafted payload can exploit the overflow to execute arbitrary code, crash the service, or alter control flow. The exposure is heightened because CockroachDB drivers and ORM integrations in Chi may batch or stream data, increasing the attack surface through large result sets or unexpected schema-driven input. Attack patterns include sending long strings in URL paths, headers, or JSON bodies that map to fixed buffers in Chi handlers, then persisting that data into CockroachDB tables without truncation or rejection. This combination of a memory-unsafe operation in the request-handling layer and a durable storage layer can turn a simple denial-of-service into a persistent compromise. The scanner’s checks for input validation and unsafe consumption are particularly relevant here, as they surface cases where untrusted data reaches buffers or database operations without adequate bounds enforcement.

Remediation focuses on strict input validation, bounded copying, and safe database interactions. In Chi, use typed middleware to validate and sanitize inputs before they reach handlers, and enforce length limits when binding request data. When writing to CockroachDB, use parameterized queries with the CockroachDB Go driver to avoid concatenating untrusted data into SQL strings, which also prevents injection that could be chained with buffer overflows. Below are concrete examples.

Example 1: Safe handler with length checks and CockroachDB insert

package main

import (
	"context"
	"fmt"
	"net/http"

	"github.com/go-chi/chi/v5"
	"github.com/jackc/pgx/v5/pgxpool"
)

func main() {
	pool, err := pgxpool.New(context.Background(), "postgres://user:pass@localhost:26257/mydb?sslmode=disable")
	if err != nil {
		panic(err)
	}
	defer pool.Close()

	r := chi.NewRouter()

	// Middleware to enforce max length on a header
	r.Use(func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			const maxHeaderLen = 256
			if len(r.Header.Get("X-Custom-ID")) > maxHeaderLen {
				http.Error(w, "header too long", http.StatusBadRequest)
				return
			}
			next.ServeHTTP(w, r)
		})
	})

	// POST /items — safe insert with bounded string
	r.Post("/items", func(w http.ResponseWriter, r *http.Request) {
		var name string
		if err := r.Decode(&name); err != nil {
			http.Error(w, "invalid request", http.StatusBadRequest)
			return
		}
		const maxNameLen = 128
		if len(name) > maxNameLen {
			http.Error(w, "name too long", http.StatusBadRequest)
			return
		}

		// Use parameterized query; CockroachDB driver handles escaping
		_, err := pool.Exec(context.Background(),
			"INSERT INTO items (id, name) VALUES ($1, $2)",
			generateID(), name)
		if err != nil {
			http.Error(w, "failed to insert", http.StatusInternalServerError)
			return
		}
		w.WriteHeader(http.StatusCreated)
	})

	// Example table schema in CockroachDB:
	// CREATE TABLE items (id UUID PRIMARY KEY, name STRING);
}

Example 2: Using prepared statements and avoiding fixed buffers

package main

import (
	"context"
	"github.com/go-chi/chi/v5"
	"github.com/jackc/pgx/v5/pgxpool"
)

func setupHandlers(pool *pgxpool.Pool, r *chi.Mux) {
	r.Post("/users/{username}", func(w http.ResponseWriter, r *http.Request) {
		username := chi.URLParam(r, "username")
		const maxUserLen = 64
		if len(username) > maxUserLen {
			http.Error(w, "username too long", http.StatusBadRequest)
			return
		}

		// Prepared statement for repeated safe execution
		stmt, err := pool.Prepare(context.Background(), "upsert_user",
			"UPSERT INTO users (username, profile) VALUES ($1, $2)")
		if err != nil {
			http.Error(w, "internal error", http.StatusInternalServerError)
			return
		}
		defer stmt.Close(context.Background())

		// Safe: bound parameters prevent injection and avoid buffer misuse
		_, err = pool.Exec(context.Background(),
			stmt, username, []byte(`{"preferences": {}}`))
		if err != nil {
			http.Error(w, "failed to upsert", http.StatusInternalServerError)
			return
		}
		w.WriteHeader(http.StatusOK)
	})
}

Key practices: validate lengths before using data in buffers or SQL, prefer Go slices with dynamic sizing, use the CockroachDB driver’s parameterized APIs, and avoid C-style buffers when interacting with the database. These steps reduce the risk of buffer overflow and ensure that data persisted in CockroachDB remains consistent and safe.