Add checks for invalid buffer ans size (#5570)

code/Common/Assimp.cpp

@@ -233,8 +233,13 @@ const aiScene *aiImportFileFromMemoryWithProperties(
         unsigned int pFlags,
         const char *pHint,
         const aiPropertyStore *props) {
-    ai_assert(nullptr != pBuffer);
-    ai_assert(0 != pLength);
+    if (pBuffer == nullptr) {
+        return nullptr;
+    }
+
+    if (pLength == 0u) {
+        return nullptr;
+    }
 
     const aiScene *scene = nullptr;
     ASSIMP_BEGIN_EXCEPTION_REGION();

test/unit/AssimpAPITest.cpp

@@ -60,3 +60,12 @@ TEST_F( AssimpAPITest, aiGetLastErrorTest ) {
     const char *error = aiGetErrorString();
     EXPECT_NE(nullptr, error);
 }
+
+TEST_F(AssimpAPITest, aiImportFileFromMemoryTest) {
+    const aiScene *scene_null_buffer = aiImportFileFromMemory(nullptr, 0u, 0u, nullptr);
+    EXPECT_EQ(nullptr, scene_null_buffer);
+
+    char buffer[1024] = {'\0'};
+    const aiScene *scene_null_size = aiImportFileFromMemory(buffer, 0u, 0u, nullptr);
+    EXPECT_EQ(nullptr, scene_null_size);
+}