fix(il2cpp): validate structural record extents (#7861)

tests/boundary/il2cpp/il2cppMetadataStructuralExtents.test.ts

@@ -0,0 +1,89 @@
+import { describe, expect, it } from "vitest";
+import { Il2cppMetadataFormatFailure } from "../../../src/il2cpp/Il2cppMetadataFormat.js";
+import { createIl2cppMetadataFixture } from "../../fixtures/il2cpp/metadata.js";
+import {
+  readIl2cppMetadata,
+  readIl2cppMetadataForLinking,
+} from "../../fixtures/il2cpp/readers.js";
+
+describe("IL2CPP structural section extents", () => {
+  it.each([24, 27, 29, 31, 39] as const)(
+    "validates generic records before inventory or linking for version %i",
+    (version) => {
+      const fixture = createIl2cppMetadataFixture({
+        version,
+        genericOwners: true,
+      });
+      for (const reader of [readIl2cppMetadata, readIl2cppMetadataForLinking]) {
+        expect(() => reader(fixture.bytes)).not.toThrow();
+        for (const name of [
+          "genericContainers",
+          "genericParameters",
+        ] as const) {
+          const damaged = Buffer.from(fixture.bytes);
+          damaged.writeInt32LE(
+            fixture.section(name).size - 1,
+            fixture.header(name, "size"),
+          );
+          expect(() => reader(damaged)).toThrow(Il2cppMetadataFormatFailure);
+          expect(() => reader(damaged)).toThrow(/record-size-mismatch/);
+        }
+      }
+    },
+  );
+
+  it.each([24, 27, 29, 31] as const)(
+    "rejects partial fixed-width interface offsets in version %i",
+    (version) => {
+      const fixture = createIl2cppMetadataFixture({
+        version,
+        genericOwners: true,
+      });
+      const damaged = Buffer.from(fixture.bytes);
+      damaged.writeInt32LE(6, fixture.header("interfaceOffsets", "size"));
+      for (const reader of [readIl2cppMetadata, readIl2cppMetadataForLinking]) {
+        expect(() => reader(fixture.bytes)).not.toThrow();
+        expect(() => reader(damaged)).toThrow(/record-size-mismatch/);
+      }
+    },
+  );
+
+  it("rejects a counted generic-parameter extent with the wrong declared count", () => {
+    const fixture = createIl2cppMetadataFixture({
+      version: 39,
+      genericOwners: true,
+    });
+    const damaged = Buffer.from(fixture.bytes);
+    damaged.writeInt32LE(3, fixture.header("genericParameters", "count"));
+    expect(() => readIl2cppMetadata(damaged)).toThrow(/record-size-mismatch/);
+  });
+
+  it.each([31, 39] as const)(
+    "uses the same extent validation for decoded member sections in version %i",
+    (version) => {
+      const fixture = createIl2cppMetadataFixture({
+        version,
+        genericOwners: true,
+        propertiesAndEvents: true,
+      });
+      for (const name of [
+        "fields",
+        "properties",
+        "events",
+        "parameters",
+        "stringLiterals",
+        "nestedTypes",
+      ] as const) {
+        expect(fixture.section(name).size, name).toBeGreaterThan(0);
+        const damaged = Buffer.from(fixture.bytes);
+        damaged.writeInt32LE(
+          fixture.section(name).size - 1,
+          fixture.header(name, "size"),
+        );
+        expect(() => readIl2cppMetadata(damaged), name).toThrow(
+          /record-size-mismatch/,
+        );
+      }
+    },
+  );
+});