Remove compile option SQLITE3MC_USE_RANDOM_FILL_MEMORY

Using random data to fill unallocated memory just incurs additional overhead without increasing security.

Author: utelle

CMakeLists.txt

@@ -64,7 +64,6 @@ OPTION(SQLITE3MC_USE_SQLCIPHER_LEGACY "Use sqlcipher legacy mode as default" OFF
 
 # Additional memory security (filling freed memory allocations with zeros or random data)
 OPTION(SQLITE3MC_SECURE_MEMORY "Enable pragma to secure freed memory" OFF)
-OPTION(SQLITE3MC_USE_RANDOM_FILL_MEMORY "Fill freed memory with random data" OFF)
 
 # Omit AES hardware support
 OPTION(SQLITE3MC_OMIT_AES_HARDWARE_SUPPORT "Omit AES hardware support" OFF)
@@ -163,12 +162,6 @@ if(SQLITE3MC_SECURE_MEMORY)
     SQLITE3MC_SECURE_MEMORY=1
   )
 endif()
-if(SQLITE3MC_USE_RANDOM_FILL_MEMORY)
-  set(SQLITE3MC_BASE_DEFINITIONS 
-    ${SQLITE3MC_BASE_DEFINITIONS}
-    SQLITE3MC_USE_RANDOM_FILL_MEMORY=1
-  )
-endif()
 
 if(SQLITE3MC_USE_MINIZ OR _SQLITE3MC_REQUIRE_ZLIB)
   if(_SQLITE3MC_REQUIRE_ZLIB)

build/config.gcc

@@ -27,7 +27,4 @@ SQLITE3MC_USE_MINIZ ?= 0
 # Set to 1 to enable the PRAGMA
 SQLITE3MC_SECURE_MEMORY ?= 0
 
-# Optionally fill freed memory with random data instead of zeros (Default: 0)
-#SQLITE3MC_USE_RANDOM_FILL_MEMORY ?= 0
-
 ### Configuration dependent settings

build/wx_setup.props

@@ -5,9 +5,6 @@
     <SQLITE_ENABLE_DEBUG>0</SQLITE_ENABLE_DEBUG>
     <SQLITE3MC_USE_MINIZ>1</SQLITE3MC_USE_MINIZ>
     <SQLITE3MC_SECURE_MEMORY>0</SQLITE3MC_SECURE_MEMORY>
-<!--
-    <SQLITE3MC_USE_RANDOM_FILL_MEMORY>0</SQLITE3MC_USE_RANDOM_FILL_MEMORY>
--->
   </PropertyGroup>
   <ItemDefinitionGroup>
     <Link>

premake5.lua

@@ -92,7 +92,6 @@ project "sqlite3mc_lib"
 --    "SQLITE_ENABLE_SQLAR=1"
 --    "SQLITE_ENABLE_ZIPFILE=1"
     "SQLITE3MC_SECURE_MEMORY=$(SQLITE3MC_SECURE_MEMORY)",
---    "SQLITE3MC_USE_RANDOM_FILL_MEMORY=$(SQLITE3MC_USE_RANDOM_FILL_MEMORY)",
     "SQLITE_TEMP_STORE=2",
     "SQLITE_USE_URI=1",
     "SQLITE_USER_AUTHENTICATION=0",
@@ -190,7 +189,6 @@ project "sqlite3mc_dll"
 --    "SQLITE_ENABLE_SQLAR=1"
 --    "SQLITE_ENABLE_ZIPFILE=1"
     "SQLITE3MC_SECURE_MEMORY=$(SQLITE3MC_SECURE_MEMORY)",
---    "SQLITE3MC_USE_RANDOM_FILL_MEMORY=$(SQLITE3MC_USE_RANDOM_FILL_MEMORY)",
     "SQLITE_TEMP_STORE=2",
     "SQLITE_USE_URI=1",
     "SQLITE_USER_AUTHENTICATION=0"
@@ -342,7 +340,6 @@ project "sqlite3mc_libicu"
 --    "SQLITE_ENABLE_SQLAR=1"
 --    "SQLITE_ENABLE_ZIPFILE=1"
     "SQLITE3MC_SECURE_MEMORY=$(SQLITE3MC_SECURE_MEMORY)",
---    "SQLITE3MC_USE_RANDOM_FILL_MEMORY=$(SQLITE3MC_USE_RANDOM_FILL_MEMORY)",
     "SQLITE_TEMP_STORE=2",
     "SQLITE_USE_URI=1",
     "SQLITE_USER_AUTHENTICATION=0",
@@ -453,7 +450,6 @@ project "sqlite3mc_dllicu"
 --    "SQLITE_ENABLE_SQLAR=1"
 --    "SQLITE_ENABLE_ZIPFILE=1"
     "SQLITE3MC_SECURE_MEMORY=$(SQLITE3MC_SECURE_MEMORY)",
---    "SQLITE3MC_USE_RANDOM_FILL_MEMORY=$(SQLITE3MC_USE_RANDOM_FILL_MEMORY)",
     "SQLITE_TEMP_STORE=2",
     "SQLITE_USE_URI=1",
     "SQLITE_USER_AUTHENTICATION=0"

src/memory_secure.c

@@ -44,38 +44,6 @@ static volatile int mcSecureMemoryFlag = 0;
 /* Map of default memory allocation methods */
 static volatile sqlite3_mem_methods mcDefaultMemoryMethods;
 
-#if SQLITE3MC_ENABLE_RANDOM_FILL_MEMORY
-
-/*
-** Fill a buffer with pseudo-random bytes.  This is used to preset
-** the content of a new memory allocation to unpredictable values and
-** to clear the content of a freed allocation to unpredictable values.
-*/
-static void mcRandomFill(char* pBuf, int nByte)
-{
-  unsigned int x, y, r;
-  x = SQLITE_PTR_TO_INT(pBuf);
-  y = nByte | 1;
-  while( nByte >= 4 )
-  {
-    x = (x>>1) ^ (-(int)(x&1) & 0xd0000001);
-    y = y*1103515245 + 12345;
-    r = x ^ y;
-    *(int*)pBuf = r;
-    pBuf += 4;
-    nByte -= 4;
-  }
-  while( nByte-- > 0 )
-  {
-    x = (x>>1) ^ (-(int)(x&1) & 0xd0000001);
-    y = y*1103515245 + 12345;
-    r = x ^ y;
-    *(pBuf++) = r & 0xff;
-  }
-}
-
-#endif
-
 /*
 ** Return the size of an allocation
 */
@@ -99,13 +67,8 @@ static void mcMemoryFree(void* pPrior)
 {
   if (mcSecureMemoryFlag)
   {
-#if SQLITE3MC_USE_RANDOM_FILL_MEMORY
-    int nSize = mcMemorySize(pPrior);
-    mcRandomFill((char*) pPrior, nSize)
-#else
     int nSize = mcMemorySize(pPrior);
     sqlite3mcSecureZeroMemory(pPrior, 0, nSize);
-#endif
   }
   mcDefaultMemoryMethods.xFree(pPrior);
 }

src/sqlite3mc.c

@@ -160,10 +160,6 @@ sqlite3mcVersion(sqlite3_context* context, int argc, sqlite3_value** argv)
 SQLITE_PRIVATE void sqlite3mcSetMemorySecurity(int value);
 SQLITE_PRIVATE int sqlite3mcGetMemorySecurity();
 
-#ifndef SQLITE3MC_USE_RANDOM_FILL_MEMORY
-#define SQLITE3MC_USE_RANDOM_FILL_MEMORY 0
-#endif
-
 /* Memory locking is currently not supported */
 #ifdef SQLITE3MC_ENABLE_MEMLOCK
 #undef SQLITE3MC_ENABLE_MEMLOCK