Fix UBSAN error in DxilRootSignatureSerializer (microsoft#5795)

amaiorano · web-flow · commit 9419b9b1c7cc · 2023-09-29T10:28:05.000-04:00
Fix UBSAN error:
```
lib/DxilRootSignature/DxilRootSignatureSerializer.cpp:134:5: runtime error: store to misaligned address 0x7fff812daf5f for type 'unsigned int', which requires 4 byte alignment
```

Use memcpy to write to unaligned address.

Fixes 63 of these reported from running check-all.
diff --git a/lib/DxilRootSignature/DxilRootSignatureSerializer.cpp b/lib/DxilRootSignature/DxilRootSignatureSerializer.cpp
@@ -131,7 +131,7 @@ HRESULT SimpleSerializer::ReserveBlock(void **ppData, unsigned cbSize,
 
   *ppData = pClonedData;
   if (pOffset) {
-    *pOffset = pSegment->Offset;
+    memcpy(pOffset, &pSegment->Offset, sizeof(pSegment->Offset));
   }
 
 Cleanup:

Original file line number	Diff line number	Diff line change
`@@ -131,7 +131,7 @@ HRESULT SimpleSerializer::ReserveBlock(void **ppData, unsigned cbSize,`
`131`	`131`
`132`	`132`	`*ppData = pClonedData;`
`133`	`133`	`if (pOffset) {`
`134`		`- *pOffset = pSegment->Offset;`
	`134`	`+ memcpy(pOffset, &pSegment->Offset, sizeof(pSegment->Offset));`
`135`	`135`	`}`
`136`	`136`
`137`	`137`	`Cleanup:`