Guard Squirrel constructor_stub() invocations from invalid class parameters

z33ky · z33ky · commit dc0cfaac0207 · 2025-06-23T21:48:07.000+02:00
This prevents manual invocations of the native class constructor for
non-class values or non-native classes.
diff --git a/sp/src/vscript/vscript_squirrel.cpp b/sp/src/vscript/vscript_squirrel.cpp
@@ -1542,7 +1542,13 @@ SQInteger destructor_stub_instance(SQUserPointer p, SQInteger size)
 SQInteger constructor_stub(HSQUIRRELVM vm)
 {
 	ScriptClassDesc_t* pClassDesc = nullptr;
-	sq_gettypetag(vm, 1, (SQUserPointer*)&pClassDesc);
+	if (SQ_FAILED(sq_gettypetag(vm, 1, (SQUserPointer*)&pClassDesc))) {
+		return sq_throwerror(vm, "Expected native class");
+	}
+
+	if (!pClassDesc || (void*)pClassDesc == TYPETAG_VECTOR) {
+		return sq_throwerror(vm, "Unable to obtain native class description");
+	}
 
 	if (!pClassDesc->m_pfnConstruct)
 	{

Original file line number	Diff line number	Diff line change
`@@ -1542,7 +1542,13 @@ SQInteger destructor_stub_instance(SQUserPointer p, SQInteger size)`
`1542`	`1542`	`SQInteger constructor_stub(HSQUIRRELVM vm)`
`1543`	`1543`	`{`
`1544`	`1544`	`ScriptClassDesc_t* pClassDesc = nullptr;`
`1545`		`- sq_gettypetag(vm, 1, (SQUserPointer*)&pClassDesc);`
	`1545`	`+ if (SQ_FAILED(sq_gettypetag(vm, 1, (SQUserPointer*)&pClassDesc))) {`
	`1546`	`+ return sq_throwerror(vm, "Expected native class");`
	`1547`	`+ }`
	`1548`	`+`
	`1549`	`+ if (!pClassDesc \|\| (void*)pClassDesc == TYPETAG_VECTOR) {`
	`1550`	`+ return sq_throwerror(vm, "Unable to obtain native class description");`
	`1551`	`+ }`
`1546`	`1552`
`1547`	`1553`	`if (!pClassDesc->m_pfnConstruct)`
`1548`	`1554`	`{`