Add explicit check for imported memory limits validity

wasmx · Mar 15, 2021 · 7b0609a · 7b0609a
1 parent 06dffc2
commit 7b0609a
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Showing 2 changed files with 9 additions and 2 deletions.
diff --git a/lib/fizzy/instantiate.cpp b/lib/fizzy/instantiate.cpp
@@ -107,6 +107,11 @@ void match_imported_memories(const std::vector<Memory>& module_imported_memories
         if (imported_memories.empty())
             throw instantiate_error{"module defines an imported memory but none was provided"};
 
+        const auto min = imported_memories[0].limits.min;
+        const auto& max = imported_memories[0].limits.max;
+        if (max.has_value() && min > *max)
+            throw instantiate_error{"provided imported memory min limit is above max limit"};
+
         match_limits(imported_memories[0].limits, module_imported_memories[0].limits);
 
         if (imported_memories[0].data == nullptr)
@@ -116,8 +121,6 @@ void match_imported_memories(const std::vector<Memory>& module_imported_memories
         if (size % PageSize != 0)
             throw instantiate_error{"provided imported memory size must be multiple of page size"};
 
-        const auto min = imported_memories[0].limits.min;
-        const auto& max = imported_memories[0].limits.max;
         if (size < min * PageSize || (max.has_value() && size > *max * PageSize))
             throw instantiate_error{"provided imported memory doesn't fit provided limits"};
     }

diff --git a/test/unittests/instantiate_test.cpp b/test/unittests/instantiate_test.cpp
@@ -283,6 +283,10 @@ TEST(instantiate, imported_memory_invalid)
     EXPECT_THROW_MESSAGE(instantiate(*module, {}, {}, {{&memory, {1, std::nullopt}}}),
         instantiate_error, "provided import's max is above import's max defined in module");
 
+    // Provided limits have max less than min
+    EXPECT_THROW_MESSAGE(instantiate(*module, {}, {}, {{&memory, {1, 0}}}), instantiate_error,
+        "provided imported memory min limit is above max limit");
+
     // Null pointer
     EXPECT_THROW_MESSAGE(instantiate(*module, {}, {}, {{nullptr, {1, 3}}}), instantiate_error,
         "provided imported memory has a null pointer to data");