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fix(memory): detect double-free of guarded allocations on 64-bit builds #18

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fix(memory): detect double-free of guarded allocations on 64-bit builds #18

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5 changes: 3 additions & 2 deletions CCPMemory.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -46,6 +46,7 @@ const int CCP_MEMORY_GUARD_SIZE_BACK = 64;
const int CCP_MEMORY_GUARD_SIZE = CCP_MEMORY_GUARD_SIZE_FRONT + CCP_MEMORY_GUARD_SIZE_BACK + sizeof( size_t );
const uint8_t CCP_MEMORY_GUARD_VALUE_FRONT = 0xee;
const uint8_t CCP_MEMORY_GUARD_VALUE_BACK = 0xef;
const size_t CCP_MEMORY_FREED_PATTERN = static_cast<size_t>( 0xddddddddddddddddULL );

// Should memory tracking in Telemetry be enabled? Defaults to yes. This can skew results of
// timing analysis of functions that do a lot of allocations, such as the yaml parser.
Expand Down Expand Up @@ -494,7 +495,7 @@ void CCPFreeWithGuard( void* p )
// Get the size
size_t orgSize = *(size_t*)p0;

if( orgSize == 0xdddddddd )
if( orgSize == CCP_MEMORY_FREED_PATTERN )
{
CCP_LOGERR( "Freeing a block that was already freed at 0x%p", p );
CCP_DEBUG_BREAK();
Expand Down Expand Up @@ -596,7 +597,7 @@ void CCPAlignedFree( void* p )

if( s_guardAllocations )
{
if( (uintptr_t)allocatedPtr == 0xdddddddd )
if( (uintptr_t)allocatedPtr == CCP_MEMORY_FREED_PATTERN )
{
CCP_LOGERR( "Freeing an aligned block that was already freed at 0x%p", p );
CCP_DEBUG_BREAK();
Expand Down
13 changes: 13 additions & 0 deletions tests/CcpMemory.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -262,6 +262,19 @@ TEST( CcpMemory, CanDetectInvalidMemoryAccessBeforeMemoryBlock )
}
}

TEST( CcpMemory, CanDetectDoubleFreeWithGuard )
{
const size_t size = 123;
void* memory = CCPMallocWithGuard( size );
EXPECT_NE( nullptr, memory );
CCPFreeWithGuard( memory );

LogHelper logHelper;
SilencedFreeWithGuard( memory );

EXPECT_TRUE( logHelper.HasMessage( CCP::LOGTYPE_ERR, "already freed" ) );
}

TEST( CcpMemory, CanDuplicateString )
{
const char* string = "just a string";
Expand Down