CVE-2019-0991

lib/Backend/GlobOpt.cpp

@@ -12827,6 +12827,26 @@ GlobOpt::ProcessValueKills(IR::Instr *const instr)
             it.RemoveCurrent();
         }
     }
+    else if(kills.KillsObjectArraysWithNoMissingValues())
+    {
+        // Some operations may kill objects with arrays-with-no-missing-values in unlikely circumstances. Convert their value types to likely
+        // versions so that the checks have to be redone.
+        for(auto it = valuesToKillOnCalls->GetIteratorWithRemovalSupport(); it.IsValid(); it.MoveNext())
+        {
+            Value *const value = it.CurrentValue();
+            ValueInfo *const valueInfo = value->GetValueInfo();
+            Assert(
+                valueInfo->IsArrayOrObjectWithArray() ||
+                valueInfo->IsOptimizedVirtualTypedArray() ||
+                valueInfo->IsOptimizedTypedArray() && valueInfo->AsArrayValueInfo()->HeadSegmentLengthSym());
+            if(!valueInfo->IsArrayOrObjectWithArray() || valueInfo->IsArray() || !valueInfo->HasNoMissingValues())
+            {
+                continue;
+            }
+            ChangeValueType(nullptr, value, valueInfo->Type().ToLikely(), false);
+            it.RemoveCurrent();
+        }
+    }
 
     if(kills.KillsNativeArrays())
     {
@@ -13358,6 +13378,11 @@ GlobOpt::CheckJsArrayKills(IR::Instr *const instr)
             {
                 kills.SetKillsArrayLengths();
             }
+
+            if(doArrayMissingValueCheckHoist && !(useValueTypes && arrayValueType.IsArray()))
+            {
+                kills.SetKillsObjectArraysWithNoMissingValues();
+            }
             break;
         }
 

lib/Backend/GlobOpt.h

@@ -317,6 +317,7 @@ private:
         {
             bool killsAllArrays : 1;
             bool killsArraysWithNoMissingValues : 1;
+            bool killsObjectArraysWithNoMissingValues : 1;
             bool killsNativeArrays : 1;
             bool killsArrayHeadSegments : 1;
             bool killsArrayHeadSegmentLengths : 1;
@@ -342,6 +343,9 @@ public:
     bool KillsArraysWithNoMissingValues() const { return killsArraysWithNoMissingValues; }
     void SetKillsArraysWithNoMissingValues() { killsArraysWithNoMissingValues = true; }
 
+    bool KillsObjectArraysWithNoMissingValues() const { return killsObjectArraysWithNoMissingValues; }
+    void SetKillsObjectArraysWithNoMissingValues() { killsObjectArraysWithNoMissingValues = true; }
+
     bool KillsNativeArrays() const { return killsNativeArrays; }
     void SetKillsNativeArrays() { killsNativeArrays = true; }