Reject malformed PDF media uploads

media/media_test.go

@@ -5,6 +5,7 @@ package media
 import (
 	"bytes"
 	"errors"
+	"fmt"
 	"image"
 	"image/color"
 	"image/jpeg"
@@ -33,7 +34,8 @@ func TestPrepareReencodesRasterAndStripsTrailingData(t *testing.T) {
 }
 
 func TestPreparePDFIsAttachment(t *testing.T) {
-	prepared, err := Prepare(strings.NewReader("%PDF-1.7\nsmall fixture"), "guide.pdf", Limits{})
+	pdf := minimalPDF()
+	prepared, err := Prepare(bytes.NewReader(pdf), "guide.pdf", Limits{})
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -42,6 +44,18 @@ func TestPreparePDFIsAttachment(t *testing.T) {
 	}
 }
 
+func TestPrepareRejectsMalformedPDF(t *testing.T) {
+	for _, source := range []string{
+		"%PDF-1.7\nsmall fixture",
+		"%PDF-9.9\nxref\ntrailer\nstartxref\n9\n%%EOF",
+		"%PDF-1.7\nxref\ntrailer\nstartxref\n999999\n%%EOF",
+	} {
+		if _, err := Prepare(strings.NewReader(source), "broken.pdf", Limits{}); !errors.Is(err, ErrInvalidMedia) {
+			t.Fatalf("malformed PDF error=%v source=%q", err, source)
+		}
+	}
+}
+
 func TestPrepareRejectsActiveAndOversizedInput(t *testing.T) {
 	if _, err := Prepare(strings.NewReader("<svg><script/></svg>"), "bad.svg", Limits{}); !errors.Is(err, ErrInvalidMedia) {
 		t.Fatalf("svg err=%v", err)
@@ -50,3 +64,9 @@ func TestPrepareRejectsActiveAndOversizedInput(t *testing.T) {
 		t.Fatalf("large err=%v", err)
 	}
 }
+
+func minimalPDF() []byte {
+	prefix := []byte("%PDF-1.7\n1 0 obj\n<< /Type /Catalog >>\nendobj\n")
+	offset := len(prefix)
+	return append(prefix, []byte(fmt.Sprintf("xref\n0 2\n0000000000 65535 f \n0000000009 00000 n \ntrailer\n<< /Size 2 /Root 1 0 R >>\nstartxref\n%d\n%%%%EOF\n", offset))...)
+}