From: Lucian Grijincu <lucian@fb.com>
Date: Mon, 9 Aug 2021 23:04:26 +0000 (-0700)
Subject: rocksdb: don't call LZ4_loadDictHC with null dictionary
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=c3034fce329017036c807e01261729bfc11a5d62;p=rocksdb.git

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
---

diff --git a/util/compression.h b/util/compression.h
index 5ce419c9..207f9949 100644
--- 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 =