[ubsan] Fix various ClusterFuzz-found issues

Fixing a few float and int overflows.
Drive-by fix: with --experimental-wasm-bigint, Number values
may not be used to initialize i64-typed globals. The existing
code for doing that relied on UB; since it's a spec violation
the fix is to throw instead.

No regression test for 933103 because it will OOM anyway.
No regression test for 932896 because it would be extremely slow.

Bug: chromium:927894, chromium:927996, chromium:930086, chromium:932679, chromium:932896, chromium:933103, chromium:933134
Change-Id: Iae1c1ff1038af4512a52d3e56b8c4b75f2233314
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1495911
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60075}

include/v8.h

@@ -10939,7 +10939,11 @@ int64_t Isolate::AdjustAmountOfExternalAllocatedMemory(
       reinterpret_cast<int64_t*>(reinterpret_cast<uint8_t*>(this) +
                                  I::kExternalMemoryAtLastMarkCompactOffset);
 
-  const int64_t amount = *external_memory + change_in_bytes;
+  // Embedders are weird: we see both over- and underflows here. Perform the
+  // addition with unsigned types to avoid undefined behavior.
+  const int64_t amount =
+      static_cast<int64_t>(static_cast<uint64_t>(change_in_bytes) +
+                           static_cast<uint64_t>(*external_memory));
   *external_memory = amount;
 
   int64_t allocation_diff_since_last_mc =

src/builtins/builtins-string.cc

@@ -448,7 +448,12 @@ BUILTIN(StringRaw) {
                                      Object::ToLength(isolate, raw_len));
 
   IncrementalStringBuilder result_builder(isolate);
-  const uint32_t length = static_cast<uint32_t>(raw_len->Number());
+  // Intentional spec violation: we ignore {length} values >= 2^32, because
+  // assuming non-empty chunks they would generate too-long strings anyway.
+  const double raw_len_number = raw_len->Number();
+  const uint32_t length = raw_len_number > std::numeric_limits<uint32_t>::max()
+                              ? std::numeric_limits<uint32_t>::max()
+                              : static_cast<uint32_t>(raw_len_number);
   if (length > 0) {
     Handle<Object> first_element;
     ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, first_element,

src/builtins/builtins-typed-array.cc

@@ -27,21 +27,18 @@ BUILTIN(TypedArrayPrototypeBuffer) {
 namespace {
 
 int64_t CapRelativeIndex(Handle<Object> num, int64_t minimum, int64_t maximum) {
-  int64_t relative;
   if (V8_LIKELY(num->IsSmi())) {
-    relative = Smi::ToInt(*num);
+    int64_t relative = Smi::ToInt(*num);
+    return relative < 0 ? std::max<int64_t>(relative + maximum, minimum)
+                        : std::min<int64_t>(relative, maximum);
   } else {
     DCHECK(num->IsHeapNumber());
-    double fp = HeapNumber::cast(*num)->value();
-    if (V8_UNLIKELY(!std::isfinite(fp))) {
-      // +Infinity / -Infinity
-      DCHECK(!std::isnan(fp));
-      return fp < 0 ? minimum : maximum;
-    }
-    relative = static_cast<int64_t>(fp);
+    double relative = HeapNumber::cast(*num)->value();
+    DCHECK(!std::isnan(relative));
+    return static_cast<int64_t>(
+        relative < 0 ? std::max<double>(relative + maximum, minimum)
+                     : std::min<double>(relative, maximum));
   }
-  return relative < 0 ? std::max<int64_t>(relative + maximum, minimum)
-                      : std::min<int64_t>(relative, maximum);
 }
 
 }  // namespace

src/compiler/representation-change.cc

@@ -977,9 +977,12 @@ Node* RepresentationChanger::GetWord64RepresentationFor(
       break;
     case IrOpcode::kNumberConstant: {
       double const fv = OpParameter<double>(node->op());
-      int64_t const iv = static_cast<int64_t>(fv);
-      if (static_cast<double>(iv) == fv) {
-        return jsgraph()->Int64Constant(iv);
+      using limits = std::numeric_limits<int64_t>;
+      if (fv <= limits::max() && fv >= limits::min()) {
+        int64_t const iv = static_cast<int64_t>(fv);
+        if (static_cast<double>(iv) == fv) {
+          return jsgraph()->Int64Constant(iv);
+        }
       }
       break;
     }

src/objects/bigint.cc

@@ -1875,7 +1875,7 @@ MaybeHandle<FreshlyAllocatedBigInt> BigInt::AllocateFor(
     bits_min = (bits_min + roundup) >> kBitsPerCharTableShift;
     if (bits_min <= static_cast<size_t>(kMaxInt)) {
       // Divide by kDigitsBits, rounding up.
-      int length = (static_cast<int>(bits_min) + kDigitBits - 1) / kDigitBits;
+      int length = static_cast<int>((bits_min + kDigitBits - 1) / kDigitBits);
       if (length <= kMaxLength) {
         Handle<MutableBigInt> result =
             MutableBigInt::New(isolate, length, pretenure).ToHandleChecked();

src/objects/fixed-array-inl.h

@@ -738,6 +738,9 @@ inline uint64_t FixedTypedArray<BigUint64ArrayTraits>::from(double value) {
 
 template <>
 inline float FixedTypedArray<Float32ArrayTraits>::from(double value) {
+  using limits = std::numeric_limits<float>;
+  if (value > limits::max()) return limits::infinity();
+  if (value < limits::lowest()) return -limits::infinity();
   return static_cast<float>(value);
 }
 

src/wasm/module-instantiate.cc

@@ -3,7 +3,9 @@
 // found in the LICENSE file.
 
 #include "src/wasm/module-instantiate.h"
+
 #include "src/asmjs/asm-js.h"
+#include "src/conversions-inl.h"
 #include "src/heap/heap-inl.h"  // For CodeSpaceMemoryModificationScope.
 #include "src/property-descriptor.h"
 #include "src/utils.h"
@@ -132,6 +134,7 @@ class InstanceBuilder {
   void LoadDataSegments(Handle<WasmInstanceObject> instance);
 
   void WriteGlobalValue(const WasmGlobal& global, double value);
+  void WriteGlobalValue(const WasmGlobal& global, int64_t num);
   void WriteGlobalValue(const WasmGlobal& global,
                         Handle<WasmGlobalObject> value);
 
@@ -647,25 +650,34 @@ void InstanceBuilder::WriteGlobalValue(const WasmGlobal& global, double num) {
   switch (global.type) {
     case kWasmI32:
       WriteLittleEndianValue<int32_t>(GetRawGlobalPtr<int32_t>(global),
-                                      static_cast<int32_t>(num));
+                                      DoubleToInt32(num));
       break;
     case kWasmI64:
-      WriteLittleEndianValue<int64_t>(GetRawGlobalPtr<int64_t>(global),
-                                      static_cast<int64_t>(num));
+      // The Wasm-BigInt proposal currently says that i64 globals may
+      // only be initialized with BigInts. See:
+      // https://github.com/WebAssembly/JS-BigInt-integration/issues/12
+      UNREACHABLE();
       break;
     case kWasmF32:
       WriteLittleEndianValue<float>(GetRawGlobalPtr<float>(global),
-                                    static_cast<float>(num));
+                                    DoubleToFloat32(num));
       break;
     case kWasmF64:
-      WriteLittleEndianValue<double>(GetRawGlobalPtr<double>(global),
-                                     static_cast<double>(num));
+      WriteLittleEndianValue<double>(GetRawGlobalPtr<double>(global), num);
       break;
     default:
       UNREACHABLE();
   }
 }
 
+void InstanceBuilder::WriteGlobalValue(const WasmGlobal& global, int64_t num) {
+  TRACE("init [globals_start=%p + %u] = %" PRId64 ", type = %s\n",
+        reinterpret_cast<void*>(raw_buffer_ptr(untagged_globals_, 0)),
+        global.offset, num, ValueTypes::TypeName(global.type));
+  DCHECK_EQ(kWasmI64, global.type);
+  WriteLittleEndianValue<int64_t>(GetRawGlobalPtr<int64_t>(global), num);
+}
+
 void InstanceBuilder::WriteGlobalValue(const WasmGlobal& global,
                                        Handle<WasmGlobalObject> value) {
   TRACE("init [globals_start=%p + %u] = ",
@@ -1045,7 +1057,7 @@ bool InstanceBuilder::ProcessImportedGlobal(Handle<WasmInstanceObject> instance,
     return true;
   }
 
-  if (value->IsNumber()) {
+  if (value->IsNumber() && global.type != kWasmI64) {
     WriteGlobalValue(global, value->Number());
     return true;
   }

test/mjsunit/regress/wasm/regress-ubsan.js

+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+load('test/mjsunit/wasm/wasm-module-builder.js');
+
+// crbug.com/933134
+(function() {
+  var builder = new WasmModuleBuilder();
+  builder.addImportedGlobal("mod", "i32", kWasmI32);
+  builder.addImportedGlobal("mod", "f32", kWasmF32);
+  var module = new WebAssembly.Module(builder.toBuffer());
+  return new WebAssembly.Instance(module, {
+    mod: {
+      i32: 1e12,
+      f32: 1e300,
+    }
+  });
+})();

test/mjsunit/ubsan-fuzzerbugs.js

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// Flags: --allow-natives-syntax
+
 // crbug.com/923466
 __v_5 = [ -1073741825, -2147483648];
 __v_5.sort();
@@ -17,3 +19,38 @@ new Date(2148022800000).toString();
 
 // crbug.com/927212
 assertThrows(() => (2n).toString(-2147483657), RangeError);
+
+// crbug.com/927894
+var typed_array = new Uint8Array(16);
+typed_array.fill(0, -1.7976931348623157e+308);
+
+// crbug.com/927996
+var float_array = new Float32Array(1);
+float_array[0] = 1e51;
+
+// crbug.com/930086
+(function() {
+  try {
+    // Build up a 536870910-character string (just under 2**30).
+    var string = "ff";
+    var long_string = "0x";
+    for (var i = 2; i < 29; i++) {
+      string = string + string;
+      long_string += string;
+    }
+    assertThrows(() => BigInt(long_string), SyntaxError);
+  } catch (e) {
+    /* 32-bit architectures have a lower string length limit. */
+  }
+})();
+
+// crbug.com/932679
+(function() {
+  const buffer = new DataView(new ArrayBuffer(2));
+  function __f_14159(buffer) {
+    try { return buffer.getUint16(Infinity, true); } catch(e) { return 0; }
+  }
+  __f_14159(buffer);
+  %OptimizeFunctionOnNextCall(__f_14159);
+  __f_14159(buffer);
+})();