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crypto: make cgo Ecrevoer not escape sig in place like precompile ecrecover #33569

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cuiweixie wants to merge 1 commit into from
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crypto: make cgo Ecrevoer not escape sig in place like precompile ecrecover #33569

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14 changes: 12 additions & 2 deletions crypto/secp256k1/secp256.go
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Original file line number Diff line number Diff line change
Expand Up @@ -43,6 +43,16 @@ func init() {
C.secp256k1_context_set_error_callback(context, C.callbackFunc(C.secp256k1GoPanicError), nil)
}

// noescape hides a pointer from escape analysis. It is the identity function
// but escape analysis doesn't think the output depends on the input.
//
//go:nosplit
//go:nocheckptr
func noescape(p unsafe.Pointer) unsafe.Pointer {
x := uintptr(p)
return unsafe.Pointer(x ^ 0)
}

var (
ErrInvalidMsgLen = errors.New("invalid message length, need 32 bytes")
ErrInvalidSignatureLen = errors.New("invalid signature length")
Expand Down Expand Up @@ -104,8 +114,8 @@ func RecoverPubkey(msg []byte, sig []byte) ([]byte, error) {

var (
pubkey = make([]byte, 65)
sigdata = (*C.uchar)(unsafe.Pointer(&sig[0]))
msgdata = (*C.uchar)(unsafe.Pointer(&msg[0]))
sigdata = (*C.uchar)(noescape(unsafe.Pointer(&sig[0])))
msgdata = (*C.uchar)(noescape(unsafe.Pointer(&msg[0])))
)
if C.secp256k1_ext_ecdsa_recover(context, (*C.uchar)(unsafe.Pointer(&pubkey[0])), sigdata, msgdata) == 0 {
return nil, ErrRecoverFailed
Expand Down