Invalid HTTP requests to Election Proclaim,Resign segfaults etcd server

[therve]

I tried to test election mechanisms over the gRPC interface, and got a segmentation. Using curl seems to make it fairly reliably:

curl -X POST -H "Content-Type: application/json" -d '{}' http://localhost:2379/v3beta/election/proclaim

curl: (52) Empty reply from server

This is the traceback:

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x38 pc=0xc83f5a]

goroutine 127 [running]:
github.com/coreos/etcd/cmd/vendor/github.com/coreos/etcd/etcdserver/api/v3election.(*electionServer).Proclaim(0xc42000d5a0, 0x160d8a0, 0xc420294360, 0xc4201a20c0, 0xc42000d5a0, 0x1006e51, 0x8)
	/home/gyuho/go/src/github.com/coreos/etcd/release/etcd/gopath/src/github.com/coreos/etcd/cmd/vendor/github.com/coreos/etcd/etcdserver/api/v3election/election.go:54 +0x3a
github.com/coreos/etcd/cmd/vendor/github.com/coreos/etcd/etcdserver/api/v3election/v3electionpb._Election_Proclaim_Handler.func1(0x160d8a0, 0xc420294360, 0xf438e0, 0xc4201a20c0, 0x1f, 0xc42026a050, 0x10358d0, 0xc4200718c8)
	/home/gyuho/go/src/github.com/coreos/etcd/release/etcd/gopath/src/github.com/coreos/etcd/cmd/vendor/github.com/coreos/etcd/etcdserver/api/v3election/v3electionpb/v3election.pb.go:452 +0x86
github.com/coreos/etcd/cmd/vendor/github.com/grpc-ecosystem/go-grpc-prometheus.(*ServerMetrics).UnaryServerInterceptor.func1(0x160d8a0, 0xc420294360, 0xf438e0, 0xc4201a20c0, 0xc4201a2100, 0xc4201a2140, 0x411648, 0x20, 0xebefa0, 0xc42026a001)
	/home/gyuho/go/src/github.com/coreos/etcd/release/etcd/gopath/src/github.com/coreos/etcd/cmd/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/server_metrics.go:112 +0xdb
github.com/coreos/etcd/cmd/vendor/github.com/coreos/etcd/etcdserver/api/v3rpc.newUnaryInterceptor.func1(0x160d8a0, 0xc420294360, 0xf438e0, 0xc4201a20c0, 0xc4201a2100, 0xc4201a2140, 0x0, 0xc4200719e0, 0x411648, 0x50)
	/home/gyuho/go/src/github.com/coreos/etcd/release/etcd/gopath/src/github.com/coreos/etcd/cmd/vendor/github.com/coreos/etcd/etcdserver/api/v3rpc/interceptor.go:57 +0xca
github.com/coreos/etcd/cmd/vendor/github.com/coreos/etcd/etcdserver/api/v3election/v3electionpb._Election_Proclaim_Handler(0xeee080, 0xc42000d5a0, 0x160d8a0, 0xc420294360, 0xc42026a000, 0xc420239d00, 0x0, 0x0, 0x0, 0x0)
	/home/gyuho/go/src/github.com/coreos/etcd/release/etcd/gopath/src/github.com/coreos/etcd/cmd/vendor/github.com/coreos/etcd/etcdserver/api/v3election/v3electionpb/v3election.pb.go:454 +0x16d
github.com/coreos/etcd/cmd/vendor/google.golang.org/grpc.(*Server).processUnaryRPC(0xc4206c4000, 0x1612d80, 0xc42012e6e0, 0xc42020c200, 0xc4201e2f30, 0x1659c38, 0x0, 0x0, 0x0)
	/home/gyuho/go/src/github.com/coreos/etcd/release/etcd/gopath/src/github.com/coreos/etcd/cmd/vendor/google.golang.org/grpc/server.go:843 +0xab4
github.com/coreos/etcd/cmd/vendor/google.golang.org/grpc.(*Server).handleStream(0xc4206c4000, 0x1612d80, 0xc42012e6e0, 0xc42020c200, 0x0)
	/home/gyuho/go/src/github.com/coreos/etcd/release/etcd/gopath/src/github.com/coreos/etcd/cmd/vendor/google.golang.org/grpc/server.go:1040 +0x1528
github.com/coreos/etcd/cmd/vendor/google.golang.org/grpc.(*Server).serveStreams.func1.1(0xc4202fd430, 0xc4206c4000, 0x1612d80, 0xc42012e6e0, 0xc42020c200)
	/home/gyuho/go/src/github.com/coreos/etcd/release/etcd/gopath/src/github.com/coreos/etcd/cmd/vendor/google.golang.org/grpc/server.go:589 +0x9f
created by github.com/coreos/etcd/cmd/vendor/google.golang.org/grpc.(*Server).serveStreams.func1
	/home/gyuho/go/src/github.com/coreos/etcd/release/etcd/gopath/src/github.com/coreos/etcd/cmd/vendor/google.golang.org/grpc/server.go:587 +0xa1

I use 3.3.1 on Fedora.

[gyuho]

I can reproduce. Will fix. Thanks for report!

[gyuho]

@therve Thanks for report. Should be fixed via #9379.
Wonder why nobody had reported this before :0