rocksdb: don't call LZ4_loadDictHC with null dictionary

Summary: UBSAN revealed a pointer underflow when `LZ4HC_init_internal` is called with a null `start`. Reviewed By: ajkr Differential Revision: D30181874 fbshipit-source-id: ca9bbac1a85c58782871d7f153af733b000cc66c
facebook · Aug 9, 2021 · c3034fc · c3034fc
1 parent 2dea3dd
commit c3034fc
Showing 1 changed file with 4 additions and 2 deletions.
diff --git a/util/compression.h b/util/compression.h
@@ -1224,8 +1224,10 @@ inline bool LZ4HC_Compress(const CompressionInfo& info,
   const char* compression_dict_data =
       compression_dict.size() > 0 ? compression_dict.data() : nullptr;
   size_t compression_dict_size = compression_dict.size();
-  LZ4_loadDictHC(stream, compression_dict_data,
-                 static_cast<int>(compression_dict_size));
+  if (compression_dict_data != nullptr) {
+    LZ4_loadDictHC(stream, compression_dict_data,
+                  static_cast<int>(compression_dict_size));
+  }
 
 #if LZ4_VERSION_NUMBER >= 10700  // r129+
   outlen =