Nil Pointer in MarshalTo/MarshalToSizedBuffer

[un000]

Got a grpc handler:

func (h *hello) Echo(ctx context.Context, req *pb.Payload) (*pb.Payload, error) {
	var res *pb.Payload    // <<<< typed nil or can be not typed
	return res, nil
}

With default grpc-library there is no panic, protobuf 1.3.2 returns to a client an error:

	ErrNil = errors.New("proto: Marshal called with nil")

But with gogofaster grpc server crashes with a panic:

[signal SIGSEGV: segmentation violation code=0x1 addr=0x8 pc=0x14964a6]

goroutine 51 [running]:
github.com/myorg/hello/example/pb.(*Payload).MarshalToSizedBuffer(0x0, 0x1ab1d58, 0x0, 0x0, 0x100bd73, 0x15879e0, 0x15fca60)
        /Users/un0/go/src/github.com/myorg/hello/example/pb/hello.pb.go:192 +0x26
github.com/myorg/hello/example/pb.(*Payload).Marshal(0x0, 0x15fca60, 0x0, 0x4a000a0, 0x0, 0x15fca01)
        /Users/un0/go/src/github.com/myorg/hello/example/pb/hello.pb.go:175 +0xc3
google.golang.org/grpc/encoding/proto.codec.Marshal(0x15fca60, 0x0, 0xc000211070, 0x0, 0x100a9bb, 0xc000012000, 0x158b820)
        /Users/un0/go/pkg/mod/google.golang.org/[email protected]/encoding/proto/proto.go:70 +0x194
google.golang.org/grpc.encode(0x4a00028, 0x1ab1d58, 0x15fca60, 0x0, 0x1ab1d58, 0x100a9bb, 0xc000012000, 0x1587f60, 0x1573ca0)
        /Users/un0/go/pkg/mod/google.golang.org/[email protected]/rpc_util.go:543 +0x52
google.golang.org/grpc.(*Server).sendResponse(0xc0000eac60, 0x16f6840, 0xc000001e00, 0xc0001ba100, 0x15fca60, 0x0, 0x0, 0x0, 0xc0001a807c, 0x0, ...)
        /Users/un0/go/pkg/mod/google.golang.org/[email protected]/server.go:833 +0x89
google.golang.org/grpc.(*Server).processUnaryRPC(0xc0000eac60, 0x16f6840, 0xc000001e00, 0xc0001ba100, 0xc00008fb90, 0x1a85230, 0x0, 0x0, 0x0)
        /Users/un0/go/pkg/mod/google.golang.org/[email protected]/server.go:1030 +0x551
google.golang.org/grpc.(*Server).handleStream(0xc0000eac60, 0x16f6840, 0xc000001e00, 0xc0001ba100, 0x0)
        /Users/un0/go/pkg/mod/google.golang.org/[email protected]/server.go:1275 +0xd97
google.golang.org/grpc.(*Server).serveStreams.func1.1(0xc00002a5c0, 0xc0000eac60, 0x16f6840, 0xc000001e00, 0xc0001ba100)
        /Users/un0/go/pkg/mod/google.golang.org/[email protected]/server.go:710 +0xbb
created by google.golang.org/grpc.(*Server).serveStreams.func1
        /Users/un0/go/pkg/mod/google.golang.org/[email protected]/server.go:708 +0xa1

Generated code:

func (m *Payload) MarshalToSizedBuffer(dAtA []byte) (int, error) {
        // if m == nil { return nil, ErrNil }

	i := len(dAtA)    // if len(dAtA) == 0 we must exit with an error, .Size method makes nil check
	_ = i
	var l int
	_ = l

	if m.Number != 0 {      // <<<< nil-pointer panic  m

There should be the check for a backward compatibility. The entire application must not to be crashed in the runtime, it must return an error. The right logic was described here https://github.com/grpc/grpc-go/issues/532#issuecomment-268056152

References https://github.com/gogo/protobuf/pull/451#issuecomment-416857142

[un000]

@awalterschulze @jmarais what do you think about that? Should I commit this change?

[alexshtin]

I am having the same problem here. Basically every time when error is nil, payload must be not nil which is really annoying. Added checks to handlers for now, but this is very error prone.

Can we fix it? I don't want to switch to standard gRCP library due to number of reasons.

[kevindiu]

Is there any update on this issue? This panic still occur in my environment and causing the application down...

[jansoneo]

gogofaster is non-thread-safe