panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x56e068]

goroutine 27 [running]:
github.com/google/syzkaller/prog.(*Prog).serialize(0x0, 0x0)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/encoding.go:40 +0x80
github.com/google/syzkaller/prog.(*Prog).Serialize(...)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/encoding.go:30
github.com/google/syzkaller/pkg/rpcserver.(*Runner).handleExecResult(0xc000126f00, 0xc00024c500)
	/syzkaller/gopath/src/github.com/google/syzkaller/pkg/rpcserver/runner.go:439 +0x17c
github.com/google/syzkaller/pkg/rpcserver.(*Runner).ConnectionLoop(0xc000126f00)
	/syzkaller/gopath/src/github.com/google/syzkaller/pkg/rpcserver/runner.go:203 +0x320
github.com/google/syzkaller/pkg/rpcserver.(*server).connectionLoop(0xc00023a800, 0xc000126f00)
	/syzkaller/gopath/src/github.com/google/syzkaller/pkg/rpcserver/rpcserver.go:356 +0xdc
github.com/google/syzkaller/pkg/rpcserver.(*server).handleRunnerConn(0xc00023a800, 0xc000126f00, 0xc001334550)
	/syzkaller/gopath/src/github.com/google/syzkaller/pkg/rpcserver/rpcserver.go:294 +0x360
github.com/google/syzkaller/pkg/rpcserver.(*server).handleConn(0xc00023a800, 0xc001334550)
	/syzkaller/gopath/src/github.com/google/syzkaller/pkg/rpcserver/rpcserver.go:261 +0x254
github.com/google/syzkaller/pkg/flatrpc.ListenAndServe.func1.1()
	/syzkaller/gopath/src/github.com/google/syzkaller/pkg/flatrpc/conn.go:55 +0x128
created by github.com/google/syzkaller/pkg/flatrpc.ListenAndServe.func1 in goroutine 7
	/syzkaller/gopath/src/github.com/google/syzkaller/pkg/flatrpc/conn.go:52 +0xb0