syscall: introduce Pointer type and use it instead of uintptr

Some syscall structures used by crypto/x509 have uintptr
fields that store pointers. These pointers are set with
a pointer to another Go structure. But the pointers are
not visible by garbage collector, and GC does not update
the fields after they were set. So when structure with
invalid uintptr pointers passed to Windows, we get
memory corruption.

This CL introduces CertInfo, CertTrustListInfo and
CertRevocationCrlInfo types. It uses pointers to new types
instead of uintptr in CertContext, CertSimpleChain and
CertRevocationInfo.

CertRevocationInfo, CertChainPolicyPara and
CertChainPolicyStatus types have uintptr field that can
be pointer to many different things (according to Windows
API). So this CL introduces Pointer type to be used for
those cases.

As suggested by Austin Clements.

Fixes #21376
Updates #24820

Change-Id: If95cd9eee3c69e4cfc35b7b25b1b40c2dc8f0df7
Reviewed-on: https://go-review.googlesource.com/106275
Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

api/except.txt

@@ -371,3 +371,15 @@ pkg text/template/parse, type VariableNode struct
 pkg text/template/parse, type VariableNode struct, Ident []string
 pkg text/template/parse, type VariableNode struct, embedded NodeType
 pkg text/template/parse, type VariableNode struct, embedded Pos
+pkg syscall (windows-386), type CertChainPolicyPara struct, ExtraPolicyPara uintptr
+pkg syscall (windows-386), type CertChainPolicyStatus struct, ExtraPolicyStatus uintptr
+pkg syscall (windows-386), type CertContext struct, CertInfo uintptr
+pkg syscall (windows-386), type CertRevocationInfo struct, CrlInfo uintptr
+pkg syscall (windows-386), type CertRevocationInfo struct, OidSpecificInfo uintptr
+pkg syscall (windows-386), type CertSimpleChain struct, TrustListInfo uintptr
+pkg syscall (windows-amd64), type CertChainPolicyPara struct, ExtraPolicyPara uintptr
+pkg syscall (windows-amd64), type CertChainPolicyStatus struct, ExtraPolicyStatus uintptr
+pkg syscall (windows-amd64), type CertContext struct, CertInfo uintptr
+pkg syscall (windows-amd64), type CertRevocationInfo struct, CrlInfo uintptr
+pkg syscall (windows-amd64), type CertRevocationInfo struct, OidSpecificInfo uintptr
+pkg syscall (windows-amd64), type CertSimpleChain struct, TrustListInfo uintptr

src/crypto/x509/root_windows.go

@@ -109,7 +109,7 @@ func checkChainSSLServerPolicy(c *Certificate, chainCtx *syscall.CertChainContex
 	sslPara.Size = uint32(unsafe.Sizeof(*sslPara))
 
 	para := &syscall.CertChainPolicyPara{
-		ExtraPolicyPara: uintptr(unsafe.Pointer(sslPara)),
+		ExtraPolicyPara: (syscall.Pointer)(unsafe.Pointer(sslPara)),
 	}
 	para.Size = uint32(unsafe.Sizeof(*para))
 

src/syscall/types_windows.go

@@ -296,6 +296,14 @@ var (
 	OID_SGC_NETSCAPE        = []byte("2.16.840.1.113730.4.1\x00")
 )
 
+// Pointer represents a pointer to an arbitrary Windows type.
+//
+// Pointer-typed fields may point to one of many different types. It's
+// up to the caller to provide a pointer to the appropriate type, cast
+// to Pointer. The caller must obey the unsafe.Pointer rules while
+// doing so.
+type Pointer *struct{}
+
 // Invented values to support what package os expects.
 type Timeval struct {
 	Sec  int32
@@ -845,11 +853,15 @@ type MibIfRow struct {
 	Descr           [MAXLEN_IFDESCR]byte
 }
 
+type CertInfo struct {
+	// Not implemented
+}
+
 type CertContext struct {
 	EncodingType uint32
 	EncodedCert  *byte
 	Length       uint32
-	CertInfo     uintptr
+	CertInfo     *CertInfo
 	Store        Handle
 }
 
@@ -864,12 +876,16 @@ type CertChainContext struct {
 	RevocationFreshnessTime    uint32
 }
 
+type CertTrustListInfo struct {
+	// Not implemented
+}
+
 type CertSimpleChain struct {
 	Size                       uint32
 	TrustStatus                CertTrustStatus
 	NumElements                uint32
 	Elements                   **CertChainElement
-	TrustListInfo              uintptr
+	TrustListInfo              *CertTrustListInfo
 	HasRevocationFreshnessTime uint32
 	RevocationFreshnessTime    uint32
 }
@@ -884,14 +900,18 @@ type CertChainElement struct {
 	ExtendedErrorInfo *uint16
 }
 
+type CertRevocationCrlInfo struct {
+	// Not implemented
+}
+
 type CertRevocationInfo struct {
 	Size             uint32
 	RevocationResult uint32
 	RevocationOid    *byte
-	OidSpecificInfo  uintptr
+	OidSpecificInfo  Pointer
 	HasFreshnessTime uint32
 	FreshnessTime    uint32
-	CrlInfo          uintptr // *CertRevocationCrlInfo
+	CrlInfo          *CertRevocationCrlInfo
 }
 
 type CertTrustStatus struct {
@@ -922,7 +942,7 @@ type CertChainPara struct {
 type CertChainPolicyPara struct {
 	Size            uint32
 	Flags           uint32
-	ExtraPolicyPara uintptr
+	ExtraPolicyPara Pointer
 }
 
 type SSLExtraCertChainPolicyPara struct {
@@ -937,7 +957,7 @@ type CertChainPolicyStatus struct {
 	Error             uint32
 	ChainIndex        uint32
 	ElementIndex      uint32
-	ExtraPolicyStatus uintptr
+	ExtraPolicyStatus Pointer
 }
 
 const (