Validate index formats in SetIndexBuffer

Fuzzer discovered that it was possible to send invalid IndexFormats
to SetIndexBuffer and cause IndexFormatSize to hit an UNREACHABLE().
This validates that the passed format is part of the enum before
doing any further operations on it.

Bug: 1254571
Change-Id: I1e4075f8d26afdb8e4bcae3cfc72e6219ff28f78
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/65610
Commit-Queue: Brandon Jones <bajones@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>

src/dawn_native/RenderEncoderBase.cpp

diff --git a/src/dawn_native/RenderEncoderBase.cpp b/src/dawn_native/RenderEncoderBase.cpp
index 993bc66..240fc29 100644
--- a/src/dawn_native/RenderEncoderBase.cpp
+++ b/src/dawn_native/RenderEncoderBase.cpp
@@ -244,6 +244,8 @@
                     DAWN_TRY(GetDevice()->ValidateObject(buffer));
                     DAWN_TRY(ValidateCanUseAs(buffer, wgpu::BufferUsage::Index));
 
+                    DAWN_TRY(ValidateIndexFormat(format));
+
                     DAWN_INVALID_IF(format == wgpu::IndexFormat::Undefined,
                                     "Index format must be specified");
 

src/tests/unittests/validation/IndexBufferValidationTests.cpp

diff --git a/src/tests/unittests/validation/IndexBufferValidationTests.cpp b/src/tests/unittests/validation/IndexBufferValidationTests.cpp
index d13bf33..d1d62b3 100644
--- a/src/tests/unittests/validation/IndexBufferValidationTests.cpp
+++ b/src/tests/unittests/validation/IndexBufferValidationTests.cpp
@@ -58,6 +58,21 @@
     ASSERT_DEVICE_ERROR(encoder.Finish());
 }
 
+// Test that an invalid index format is disallowed.
+TEST_F(IndexBufferValidationTest, InvalidIndexFormat) {
+    wgpu::BufferDescriptor bufferDesc;
+    bufferDesc.usage = wgpu::BufferUsage::Index;
+    bufferDesc.size = 256;
+    wgpu::Buffer buffer = device.CreateBuffer(&bufferDesc);
+
+    DummyRenderPass renderPass(device);
+    wgpu::CommandEncoder encoder = device.CreateCommandEncoder();
+    wgpu::RenderPassEncoder pass = encoder.BeginRenderPass(&renderPass);
+    pass.SetIndexBuffer(buffer, static_cast<wgpu::IndexFormat>(404));
+    pass.EndPass();
+    ASSERT_DEVICE_ERROR(encoder.Finish());
+}
+
 // Test that for OOB validation of index buffer offset and size.
 TEST_F(IndexBufferValidationTest, IndexBufferOffsetOOBValidation) {
     wgpu::BufferDescriptor bufferDesc;