panic: bad arg kind: <nil>

goroutine 26 [running]:
github.com/google/syzkaller/prog.clone(0x0, 0x0, 0xc000163e38, 0xc000d03d40, 0xc000163a80)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/clone.go:79 +0x91b
github.com/google/syzkaller/prog.clone(0x9b2c80, 0xc002de9740, 0xc000163e38, 0xc001dfcf50, 0xc000163b80)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/clone.go:57 +0x18d
github.com/google/syzkaller/prog.clone(0x9b2c80, 0xc002de99c0, 0xc000163e38, 0x9b2c00, 0xc002373bf0)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/clone.go:57 +0x18d
github.com/google/syzkaller/prog.clone(0x9b2c80, 0xc002de99e0, 0xc000163e38, 0xc000163eb0, 0xc000163d80)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/clone.go:57 +0x18d
github.com/google/syzkaller/prog.clone(0x9b2cc0, 0xc00275c750, 0xc000163e38, 0x9b2c00, 0xc002373b80)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/clone.go:44 +0x567
github.com/google/syzkaller/prog.(*Prog).Clone(0xc00271fec0, 0xc002dec210)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/clone.go:24 +0x279
main.(*Proc).loop(0xc002dd2300)
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/proc.go:94 +0x3ca
created by main.main
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/fuzzer.go:260 +0x1188