From 6bac05a057252528b7a4dc3a6513189ef2dde876 Mon Sep 17 00:00:00 2001
From: David Carlier <dcarlier@afilias.info>
Date: Thu, 9 Aug 2018 12:57:28 +0000
Subject: [PATCH] Fix overflow by getting the chunk size during reallocation

---
 Makefile            | 2 +-
 engine/lib/memory.c | 6 +++++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index 0385608..b741166 100644
--- a/Makefile
+++ b/Makefile
@@ -151,7 +151,7 @@ $(SAPI):
 	$(eval SAPI_OBJS := $(addprefix $(BUILD_DIR)/,$(SAPI_MAKE)))
 	$(eval SAPI_PROG := $(subst -cli,,$(BINARY)-$(SAPI_DIRS))$(EXESUFFIX))
 	$(MAKE) $(SAPI_OBJS)
-	$(CC) -o $(BUILD_DIR)/$(SAPI_PROG) $(LDFLAGS) $(LIBFLAGS) $(SAPI_OBJS)
+	$(CC) -o $(BUILD_DIR)/$(SAPI_PROG) $(LDFLAGS) $(SAPI_OBJS) $(LIBFLAGS) $(LIBS)
 
 %.test: %.exp %.$(TEST_EXT)
 	@$(MD) ${BUILD_DIR}/${TEST_DIR}
diff --git a/engine/lib/memory.c b/engine/lib/memory.c
index 01c661e..f3a798b 100644
--- a/engine/lib/memory.c
+++ b/engine/lib/memory.c
@@ -118,6 +118,7 @@ static void *MemOSAlloc(sxu32 nBytes, SyMemBackend *pBackend) {
 static void *MemOSRealloc(void *pOld, sxu32 nBytes, SyMemBackend *pBackend) {
 	sxu32 *pOldChunk;
 	sxu32 *pChunk;
+	sxu32 pBytes = nBytes;
 	CheckHeap(pBackend, nBytes);
 	pOldChunk = (sxu32 *)(((char *)pOld) - sizeof(sxu32));
 	if(pOldChunk[0] >= nBytes) {
@@ -128,7 +129,10 @@ static void *MemOSRealloc(void *pOld, sxu32 nBytes, SyMemBackend *pBackend) {
 		return 0;
 	}
 	pChunk[0] = nBytes;
-	AddToHeap(pBackend, abs(nBytes - pOldChunk[0]));
+	if(pOldChunk) {
+		pBytes -= pBackend->pMethods->xChunkSize(pOldChunk);
+	}
+	AddToHeap(pBackend, pBytes);
 	return (void *)&pChunk[1];
 }
 static void MemOSFree(void *pBlock, SyMemBackend *pBackend) {