fix(native): bound PE resource RVAs by section virtual size (#1678)

The PE resource reader treated each section as covering
`max(VirtualSize, SizeOfRawData)` bytes, the mapping #1596 removed from
managed RVA reads. A resource payload in the raw alignment padding past
VirtualSize was reported with a hash of bytes the image loader never maps.
A later section whose virtual range starts inside that padding was refused
as an overlapping mapping.

Containment and overlap now use the loader's virtual extent: VirtualSize,
or SizeOfRawData when VirtualSize is zero. Ranges must still be file-backed.

Refs #1596

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

src/native/pe/PeResourceLayout.ts

@@ -28,6 +28,11 @@ interface Section {
   readonly size: number;
 }
 
+// The image loader maps VirtualSize bytes, using SizeOfRawData only when
+// VirtualSize is zero. Raw bytes past that extent are file-alignment padding.
+const virtualExtent = (section: Section): number =>
+  section.virtualSize === 0 ? section.size : section.virtualSize;
+
 /** Header admission and unambiguous file-backed RVA mapping, independent of section names. */
 export const readPeResourceLayout = (bytes: Buffer) => {
   requirePeRange(bytes, 0, 64);
@@ -64,7 +69,7 @@ export const readPeResourceLayout = (bytes: Buffer) => {
       offset: bytes.readUInt32LE(at + 20),
       size: bytes.readUInt32LE(at + 16),
     };
-    if (section.rva + Math.max(section.virtualSize, section.size) > 0x100000000)
+    if (section.rva + virtualExtent(section) > 0x100000000)
       peFailure("PE section RVA range overflows.");
     if (section.size > 0) {
       requirePeRange(bytes, section.offset, section.size);
@@ -90,15 +95,14 @@ export const readPeResourceLayout = (bytes: Buffer) => {
     if (rva + size > 0x100000000) peFailure("Resource RVA range overflows.");
     const candidates = sections.filter(
       (section) =>
-        rva >= section.rva &&
-        rva - section.rva < Math.max(section.size, section.virtualSize),
+        rva >= section.rva && rva - section.rva < virtualExtent(section),
     );
     if (rva < headerSize) {
       if (
         sections.some(
           (section) =>
             section.rva < rva + size &&
-            section.rva + Math.max(section.size, section.virtualSize) > rva,
+            section.rva + virtualExtent(section) > rva,
         ) ||
         size > headerSize - rva
       )
@@ -111,6 +115,8 @@ export const readPeResourceLayout = (bytes: Buffer) => {
     const section = candidates[0];
     if (section === undefined) return peFailure("Missing resource section.");
     const within = rva - section.rva;
+    if (size > virtualExtent(section) - within)
+      peFailure("Resource range leaves its section's virtual size.");
     if (within > section.size || size > section.size - within)
       peFailure("Resource range is not entirely file-backed in one section.");
     // A second section starting inside the requested interval is ambiguous too.
@@ -119,7 +125,7 @@ export const readPeResourceLayout = (bytes: Buffer) => {
         (other) =>
           other !== section &&
           other.rva < rva + size &&
-          other.rva + Math.max(other.size, other.virtualSize) > rva,
+          other.rva + virtualExtent(other) > rva,
       )
     )
       peFailure("Resource interval intersects overlapping virtual sections.");

src/native/pe/PeResourceParser.test.ts

@@ -259,3 +259,62 @@ describe("PE header admission and bounded traversal", () => {
     await expect(parsing).rejects.toThrow();
   });
 });
+
+describe("PE resource section virtual extent", () => {
+  const sectionSizes = (fixture: ReturnType<typeof peResourceFixture>) => {
+    const virtualSize = fixture.bytes.readUInt32LE(fixture.sectionAt + 8);
+    const rawSize = fixture.bytes.readUInt32LE(fixture.sectionAt + 16);
+    expect(rawSize - virtualSize).toBeGreaterThanOrEqual(8);
+    return { virtualSize, rawSize };
+  };
+
+  it.each([
+    [0, "Resource RVA has missing or overlapping section mappings."],
+    [-2, "Resource range leaves its section's virtual size."],
+  ])(
+    "rejects a payload reaching raw alignment padding past VirtualSize (start %i)",
+    async (start, message) => {
+      const fixture = peResourceFixture();
+      const { virtualSize } = sectionSizes(fixture);
+      const rva = 0x2000 + virtualSize + start;
+      fixture.bytes.writeUInt32LE(rva, fixture.dataOffsets[0]);
+      fixture.bytes.writeUInt32LE(4, (fixture.dataOffsets[0] ?? 0) + 4);
+      await expect(parse(fixture.bytes)).rejects.toMatchObject({
+        reason: "format",
+        message,
+      });
+    },
+  );
+
+  it("maps raw bytes when VirtualSize is zero, as the image loader does", async () => {
+    const fixture = peResourceFixture();
+    fixture.bytes.writeUInt32LE(0, fixture.sectionAt + 8);
+    expect(await parse(fixture.bytes)).toMatchObject({
+      coverage: { status: "complete", resources: 5 },
+    });
+  });
+
+  it("selects a later section that starts inside earlier raw padding", async () => {
+    const fixture = peResourceFixture();
+    const { virtualSize } = sectionSizes(fixture);
+    const laterRva = 0x2000 + Math.ceil(virtualSize / 4) * 4;
+    const rawOffset = fixture.bytes.length;
+    const payload = Buffer.from("LATE");
+    const bytes = Buffer.concat([fixture.bytes, payload]);
+    bytes.writeUInt16LE(2, 0x86);
+    const later = fixture.sectionAt + 40;
+    bytes.writeUInt32LE(payload.length, later + 8);
+    bytes.writeUInt32LE(laterRva, later + 12);
+    bytes.writeUInt32LE(payload.length, later + 16);
+    bytes.writeUInt32LE(rawOffset, later + 20);
+    bytes.writeUInt32LE(laterRva, fixture.dataOffsets[0]);
+    bytes.writeUInt32LE(payload.length, (fixture.dataOffsets[0] ?? 0) + 4);
+
+    const result = peResourcesSchema.parse(await parse(bytes));
+    expect(result.resources[0]?.payload).toMatchObject({
+      rva: laterRva,
+      location: { offset: rawOffset, bytes: payload.length },
+      sha256: createHash("sha256").update(payload).digest("hex"),
+    });
+  });
+});