fix: bound network response body reads

cli/cmd/model_pull.go

@@ -109,11 +109,15 @@ func (r *runners) pullModel(cmd *cobra.Command, args []string) error {
 	}
 	defer manifestContent.Close()
 
-	// Read the manifest content into a byte slice
-	manifestBytes, err := io.ReadAll(manifestContent)
+	// Read the manifest content into a byte slice (OCI manifests are small JSON).
+	const maxManifestBody = 16 << 20 // 16 MiB
+	manifestBytes, err := io.ReadAll(io.LimitReader(manifestContent, maxManifestBody+1))
 	if err != nil {
 		return err
 	}
+	if len(manifestBytes) > maxManifestBody {
+		return fmt.Errorf("OCI manifest exceeds %d bytes", maxManifestBody)
+	}
 
 	var manifest v1.Manifest
 	if err := json.Unmarshal(manifestBytes, &manifest); err != nil {

pkg/cmxmetadata/cmxmetadata.go

@@ -17,6 +17,8 @@ const (
 	mmdsPath     = "/latest/vendor-api"
 	mmdsTimeout  = 500 * time.Millisecond // fail fast if not in CMX
 	tokenLeeway  = 60 * time.Second       // refresh token this early before expiry
+	// maxMetadataBody bounds MMDS / token JSON responses (credentials, not archives).
+	maxMetadataBody = 1 << 20 // 1 MiB
 )
 
 // ErrNotAvailable is returned when the CMX metadata service is not reachable.
@@ -61,7 +63,7 @@ func GetVMMetadata() (*VMMetadata, error) {
 		return nil, ErrNotAvailable
 	}
 
-	body, err := io.ReadAll(resp.Body)
+	body, err := readAllLimited(resp.Body, maxMetadataBody)
 	if err != nil {
 		return nil, ErrNotAvailable
 	}
@@ -140,7 +142,7 @@ func exchangeCredentials(meta *VMMetadata) (string, *time.Time, error) {
 	}
 	defer resp.Body.Close()
 
-	body, err := io.ReadAll(resp.Body)
+	body, err := readAllLimited(resp.Body, maxMetadataBody)
 	if err != nil {
 		return "", nil, fmt.Errorf("reading token response body: %w", err)
 	}
@@ -166,3 +168,14 @@ func exchangeCredentials(meta *VMMetadata) (string, *time.Time, error) {
 
 	return tokenResp.AccessToken, expiresAt, nil
 }
+
+func readAllLimited(r io.Reader, limit int64) ([]byte, error) {
+	body, err := io.ReadAll(io.LimitReader(r, limit+1))
+	if err != nil {
+		return nil, err
+	}
+	if int64(len(body)) > limit {
+		return nil, fmt.Errorf("response body exceeds %d bytes", limit)
+	}
+	return body, nil
+}

pkg/credentials/fetch.go

@@ -122,10 +122,15 @@ func exchangeNonceForToken(uri string, nonce string) (string, error) {
 		return "", fmt.Errorf("unexpected status code: %d", resp.StatusCode)
 	}
 
-	b, err := io.ReadAll(resp.Body)
+	// Token JSON is small; bound allocation against a hostile exchange endpoint.
+	const maxTokenResponse = 1 << 20 // 1 MiB
+	b, err := io.ReadAll(io.LimitReader(resp.Body, maxTokenResponse+1))
 	if err != nil {
 		return "", err
 	}
+	if len(b) > maxTokenResponse {
+		return "", fmt.Errorf("token response exceeds %d bytes", maxTokenResponse)
+	}
 
 	type tokenResponse struct {
 		Token string `json:"token"`

pkg/tools/checksum.go

@@ -15,6 +15,9 @@ var checksumHTTPClient = &http.Client{
 	Timeout: 30 * time.Second,
 }
 
+// maxChecksumBody bounds checksum text files (not the archives themselves).
+const maxChecksumBody = 1 << 20 // 1 MiB
+
 // VerifyHelmChecksum verifies a Helm binary against its .sha256sum file
 func VerifyHelmChecksum(data []byte, archiveURL string) error {
 	// Helm provides per-file checksums: <url>.sha256sum
@@ -31,7 +34,7 @@ func VerifyHelmChecksum(data []byte, archiveURL string) error {
 		return fmt.Errorf("checksum file not found (HTTP %d): %s", resp.StatusCode, checksumURL)
 	}
 
-	checksumData, err := io.ReadAll(resp.Body)
+	checksumData, err := readAllLimited(resp.Body, maxChecksumBody)
 	if err != nil {
 		return fmt.Errorf("reading checksum file: %w", err)
 	}
@@ -71,7 +74,7 @@ func VerifyTroubleshootChecksum(data []byte, version, filename string) error {
 		return fmt.Errorf("checksums file not found (HTTP %d): %s", resp.StatusCode, checksumURL)
 	}
 
-	checksumData, err := io.ReadAll(resp.Body)
+	checksumData, err := readAllLimited(resp.Body, maxChecksumBody)
 	if err != nil {
 		return fmt.Errorf("reading checksums file: %w", err)
 	}
@@ -102,3 +105,14 @@ func VerifyTroubleshootChecksum(data []byte, version, filename string) error {
 
 	return nil
 }
+
+func readAllLimited(r io.Reader, limit int64) ([]byte, error) {
+	body, err := io.ReadAll(io.LimitReader(r, limit+1))
+	if err != nil {
+		return nil, err
+	}
+	if int64(len(body)) > limit {
+		return nil, fmt.Errorf("response body exceeds %d bytes", limit)
+	}
+	return body, nil
+}

pkg/tools/checksum_limit_test.go

@@ -0,0 +1,23 @@
+package tools
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestReadAllLimited(t *testing.T) {
+	t.Parallel()
+
+	got, err := readAllLimited(strings.NewReader("abc"), 10)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if string(got) != "abc" {
+		t.Fatalf("got %q, want abc", got)
+	}
+
+	_, err = readAllLimited(strings.NewReader(strings.Repeat("x", 5)), 4)
+	if err == nil {
+		t.Fatal("expected error when body exceeds limit")
+	}
+}