[wasm] Fix ordering constraint on exception section

R=mstarzinger@chromium.org

Bug: v8:8091
Change-Id: I9564b7836667089112b958f1e8644b35ffa855a8
Reviewed-on: https://chromium-review.googlesource.com/c/1352301
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57904}

src/wasm/module-decoder.cc

@@ -361,7 +361,7 @@ class ModuleDecoderImpl : public Decoder {
         } else if (next_ordered_section_ > kExportSectionCode) {
           errorf(pc(), "Exception section must appear before export section");
           return;
-        } else if (next_ordered_section_ < kImportSectionCode) {
+        } else if (next_ordered_section_ <= kImportSectionCode) {
           next_ordered_section_ = kImportSectionCode + 1;
         }
         seen_unordered_sections_ |= 1 << kExceptionSectionCode;

test/unittests/wasm/module-decoder-unittest.cc

@@ -585,6 +585,18 @@ TEST_F(WasmModuleVerifyTest, ExceptionSectionBeforeImport) {
   EXPECT_NOT_OK(result, "unexpected section: Import");
 }
 
+TEST_F(WasmModuleVerifyTest, ExceptionSectionAfterTypeBeforeImport) {
+  STATIC_ASSERT(kTypeSectionCode + 1 == kImportSectionCode);
+  static const byte data[] = {SECTION(Type, ENTRY_COUNT(0)),
+                              SECTION(Exception, ENTRY_COUNT(0)),
+                              SECTION(Import, ENTRY_COUNT(0))};
+  FAIL_IF_NO_EXPERIMENTAL_EH(data);
+
+  WASM_FEATURE_SCOPE(eh);
+  ModuleResult result = DecodeModule(data, data + sizeof(data));
+  EXPECT_NOT_OK(result, "unexpected section: Import");
+}
+
 TEST_F(WasmModuleVerifyTest, ExceptionImport) {
   static const byte data[] = {
       SIGNATURES_SECTION_VOID_VOID,