panic: runtime error: index out of range [300252880] with length 992

goroutine 68 [running]:
github.com/google/syzkaller/prog.ArgCommon.Type(...)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/prog.go:61
github.com/google/syzkaller/prog.(*GroupArg).serialize(0xc001c94e40, 0xc00158d770)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/encoding.go:193 +0x1ab
github.com/google/syzkaller/prog.(*serializer).arg(0xc99998?, {0xc998d8?, 0xc001c94e40?})
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/encoding.go:121 +0x29
github.com/google/syzkaller/prog.(*GroupArg).serialize(0xc001c94e20, 0xc00158d770)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/encoding.go:199 +0x245
github.com/google/syzkaller/prog.(*serializer).arg(0xc91180?, {0xc998d8?, 0xc001c94e20?})
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/encoding.go:121 +0x29
github.com/google/syzkaller/prog.(*PointerArg).serialize(0xc001fc9f20, 0xc00158d770)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/encoding.go:142 +0x3a5
github.com/google/syzkaller/prog.(*serializer).arg(0xc91180?, {0xc999d8?, 0xc001fc9f20?})
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/encoding.go:121 +0x29
github.com/google/syzkaller/prog.(*serializer).call(0xc00158d770, 0xc001ff7630)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/encoding.go:82 +0x211
github.com/google/syzkaller/prog.(*Prog).serialize(0xc001969640, 0x0)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/encoding.go:46 +0xcd
github.com/google/syzkaller/prog.(*Prog).Serialize(...)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/encoding.go:30
main.(*Proc).logProgram(0xc0011db980, 0xc91200?, 0xc?)
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/proc.go:367 +0x3e
main.(*Proc).executeRaw(0xc0011db980, 0xc00199f0c0?, 0xc001969640, 0x8)
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/proc.go:336 +0x130
main.(*Proc).executeAndCollide(0xc0011db980, 0xb94f6e?, 0xc00140c9c0?, 0xc000e29f38?, 0xc001837580?)
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/proc.go:298 +0x6c
main.(*Proc).loop(0xc0011db980)
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/proc.go:97 +0x3d7
created by main.main in goroutine 1
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/fuzzer.go:336 +0x1665