Check wasm->native pointer validity based on active pages

Previously the wasm->native invoke wrapper would validate wasm pointers based on their validity in the mapped memory pages. This only means the pointer lied within the 12GB virtual memory map. So it was trival to hand off a pointer from wasm->native that would segv when native code accessed it. This is caught (and handled) but preference is for there to be no way to segv inside of native code to prevent any oddities from longjmping.

Now, check that the pointer lies within the "active" memory pages -- pages that are R/Wable

libraries/chain/include/eosio/chain/wasm_interface_private.hpp

@@ -180,7 +180,12 @@ auto convert_native_to_wasm(const wasm_interface &wasm, const fc::time_point_sec
 
 auto convert_native_to_wasm(wasm_interface &wasm, char* ptr) {
    auto mem = getDefaultMemory(intrinsics_accessor::get_context(wasm).code.instance);
-   char* base = &memoryRef<char>(mem, 0);
+   if(!mem)
+      Runtime::causeException(Exception::Cause::accessViolation);
+   char* base = (char*)getMemoryBaseAddress(mem);
+   char* top_of_memory = base + IR::numBytesPerPage*Runtime::getMemoryNumPages(mem);
+   if(ptr < base || ptr >= top_of_memory)
+      Runtime::causeException(Exception::Cause::accessViolation);
    return (int)(ptr - base);
 }
 
@@ -380,7 +385,9 @@ struct intrinsic_invoker_impl<Ret, std::tuple<array_ptr<T>, size_t, Inputs...>,
    static Ret translate_one(wasm_interface &wasm, Inputs... rest, Translated... translated, I32 ptr, I32 size) {
       auto mem = getDefaultMemory(intrinsics_accessor::get_context(wasm).code.instance);
       size_t length = size_t(size);
-      T *base = memoryArrayPtr<T>(mem, ptr, length);
+      if(!mem || ptr+sizeof(T)*length >= IR::numBytesPerPage*Runtime::getMemoryNumPages(mem))
+         Runtime::causeException(Exception::Cause::accessViolation);
+      T *base = (T*)(getMemoryBaseAddress(mem)+ptr);
       return Then(wasm, array_ptr<T>{base}, length, rest..., translated...);
    };
 
@@ -408,8 +415,11 @@ struct intrinsic_invoker_impl<Ret, std::tuple<array_ptr<T>, array_ptr<U>, size_t
    static Ret translate_one(wasm_interface &wasm, Inputs... rest, Translated... translated, I32 ptr_t, I32 ptr_u, I32 size) {
       auto mem = getDefaultMemory(intrinsics_accessor::get_context(wasm).code.instance);
       size_t length = size_t(size);
-      T *base_t = memoryArrayPtr<T>(mem, ptr_t, length);
-      U *base_u = memoryArrayPtr<U>(mem, ptr_u, length);
+      if(!mem || ptr_t+sizeof(T)*length >= IR::numBytesPerPage*Runtime::getMemoryNumPages(mem)
+              || ptr_u+sizeof(U)*length >= IR::numBytesPerPage*Runtime::getMemoryNumPages(mem))
+         Runtime::causeException(Exception::Cause::accessViolation);
+      T *base_t = (T*)(getMemoryBaseAddress(mem)+ptr_t);
+      U *base_u = (U*)(getMemoryBaseAddress(mem)+ptr_u);
       return Then(wasm, array_ptr<T>{base_t}, array_ptr<U>{base_u}, length, rest..., translated...);
    };
 
@@ -435,7 +445,9 @@ struct intrinsic_invoker_impl<Ret, std::tuple<array_ptr<char>, int, size_t>, std
    static Ret translate_one(wasm_interface &wasm, I32 ptr, I32 value, I32 size) {
       auto mem = getDefaultMemory(intrinsics_accessor::get_context(wasm).code.instance);
       size_t length = size_t(size);
-      char *base = memoryArrayPtr<char>(mem, ptr, length);
+      if(!mem || ptr+sizeof(char)*length >= IR::numBytesPerPage*Runtime::getMemoryNumPages(mem))
+         Runtime::causeException(Exception::Cause::accessViolation);
+      char *base = (char*)(getMemoryBaseAddress(mem)+ptr);
       return Then(wasm, array_ptr<char>{base}, value, length);
    };
 
@@ -462,7 +474,9 @@ struct intrinsic_invoker_impl<Ret, std::tuple<T *, Inputs...>, std::tuple<Transl
    template<then_type Then>
    static Ret translate_one(wasm_interface &wasm, Inputs... rest, Translated... translated, I32 ptr) {
       auto mem = getDefaultMemory(intrinsics_accessor::get_context(wasm).code.instance);
-      T *base = memoryArrayPtr<T>(mem, ptr, 1);
+      if(!mem || ptr+sizeof(T) >= IR::numBytesPerPage*Runtime::getMemoryNumPages(mem))
+         Runtime::causeException(Exception::Cause::accessViolation);
+      T *base = (T*)(getMemoryBaseAddress(mem)+ptr);
       return Then(wasm, base, rest..., translated...);
    };
 
@@ -544,7 +558,9 @@ struct intrinsic_invoker_impl<Ret, std::tuple<T &, Inputs...>, std::tuple<Transl
       // references cannot be created for null pointers
       FC_ASSERT(ptr != 0);
       auto mem = getDefaultMemory(intrinsics_accessor::get_context(wasm).code.instance);
-      T &base = memoryRef<T>(mem, ptr);
+      if(!mem || ptr+sizeof(T) >= IR::numBytesPerPage*Runtime::getMemoryNumPages(mem))
+         Runtime::causeException(Exception::Cause::accessViolation);
+      T &base = *(T*)(getMemoryBaseAddress(mem)+ptr);
       return Then(wasm, base, rest..., translated...);
    }