panic: UserChainTarget should never be called.

goroutine 1110 gp=0x5401b19fc960 m=26 mp=0x5401b1288808 [running]:
panic({0xd05280?, 0x10526f0?})
	GOROOT/src/runtime/panic.go:879 +0x15c fp=0x5401b201bf00 sp=0x5401b201be50 pc=0x960ac
gvisor.dev/gvisor/pkg/tcpip/stack.(*UserChainTarget).Action(...)
	pkg/tcpip/stack/iptables_targets.go:174
gvisor.dev/gvisor/pkg/sentry/socket/netfilter.(*userChainTarget).Action(0x0?, 0x0?, 0x0?, 0x10?, {0x0?, 0x0?})
	<autogenerated>:1 +0x30 fp=0x5401b201bf20 sp=0x5401b201bf00 pc=0x6ffbf0
gvisor.dev/gvisor/pkg/tcpip/stack.(*IPTables).checkRule(0x5401b1864340?, 0x1, 0x5401b173eb00, {{0x5401b185d808, 0x4, 0x4}, {0xffffffffffffffff, 0x1, 0x2, 0x0, ...}, ...}, ...)
	pkg/tcpip/stack/iptables.go:774 +0x1b0 fp=0x5401b201c130 sp=0x5401b201bf20 pc=0x5d4ea0
gvisor.dev/gvisor/pkg/tcpip/stack.(*IPTables).checkChain(0x5401b1c91c08, 0x1, 0x5401b173eb00, {{0x5401b185d808, 0x4, 0x4}, {0xffffffffffffffff, 0x1, 0x2, 0x0, ...}, ...}, ...)
	pkg/tcpip/stack/iptables.go:705 +0xb0 fp=0x5401b201c220 sp=0x5401b201c130 pc=0x5d4b20
gvisor.dev/gvisor/pkg/tcpip/stack.(*IPTables).check(0x5401b1c91c08?, {{0x5401b185d808, 0x4, 0x4}, {0xffffffffffffffff, 0x1, 0x2, 0x0, 0xffffffffffffffff}, {0xffffffffffffffff, ...}}, ...)
	pkg/tcpip/stack/iptables.go:650 +0xa0 fp=0x5401b201c3f0 sp=0x5401b201c220 pc=0x5d46e0
gvisor.dev/gvisor/pkg/tcpip/stack.check(0x80fe?, {{0x5401b185d808, 0x4, 0x4}, {0xffffffffffffffff, 0x1, 0x2, 0x0, 0xffffffffffffffff}, {0xffffffffffffffff, ...}}, ...)
	pkg/tcpip/stack/iptables.go:640 +0x58 fp=0x5401b201c4c0 sp=0x5401b201c3f0 pc=0x5d45f8
gvisor.dev/gvisor/pkg/tcpip/stack.(*IPTables).CheckInput(0x5401b1c91c08, 0x5401b173eb00, {0x5401b1639008, 0x7})
	pkg/tcpip/stack/iptables.go:459 +0x188 fp=0x5401b201c7f0 sp=0x5401b201c4c0 pc=0x5d3c48
gvisor.dev/gvisor/pkg/tcpip/network/ipv6.(*endpoint).deliverPacketLocally(0x5401b163b508, {0x5401b190cd0e, 0x28, 0x72}, 0x5401b173eb00, {0x5401b1639008?, 0x5?})
	pkg/tcpip/network/ipv6/ipv6.go:1436 +0x88 fp=0x5401b201ca50 sp=0x5401b201c7f0 pc=0x77c5d8
gvisor.dev/gvisor/pkg/tcpip/network/ipv6.(*endpoint).handleValidatedPacket(0x5401b163b508, {0x5401b190cd0e, 0x28, 0x72}, 0x5401b173eb00, {0x5401b1639008, 0x7})
	pkg/tcpip/network/ipv6/ipv6.go:1425 +0x4b8 fp=0x5401b201cd40 sp=0x5401b201ca50 pc=0x77c4f8
gvisor.dev/gvisor/pkg/tcpip/network/ipv6.(*endpoint).HandlePacket(0x5401b163b508, 0x5401b173eb00)
	pkg/tcpip/network/ipv6/ipv6.go:1195 +0x740 fp=0x5401b201d2a0 sp=0x5401b201cd40 pc=0x77a880
gvisor.dev/gvisor/pkg/tcpip/stack.(*nic).DeliverNetworkPacket(0x5401b12ac6c8, 0x86dd, 0x5401b173eb00)
	pkg/tcpip/stack/nic.go:781 +0x1a0 fp=0x5401b201d2e0 sp=0x5401b201d2a0 pc=0x5e0b80
gvisor.dev/gvisor/pkg/tcpip/link/nested.(*Endpoint).DeliverNetworkPacket(0x5401b201d348?, 0x86dd, 0x5401b173eb00)
	pkg/tcpip/link/nested/nested.go:61 +0xa8 fp=0x5401b201d320 sp=0x5401b201d2e0 pc=0x799048
gvisor.dev/gvisor/pkg/tcpip/link/packetsocket.(*Endpoint).DeliverNetworkPacket(0x5401b2086370, 0x86dd, 0x5401b173eb00)
	pkg/tcpip/link/packetsocket/packetsocket.go:50 +0x3c fp=0x5401b201d350 sp=0x5401b201d320 pc=0x79a7dc
gvisor.dev/gvisor/pkg/tcpip/link/channel.(*Endpoint).InjectInbound(0x5401b1744360, 0x86dd, 0x5401b173eb00)
	pkg/tcpip/link/channel/channel.go:208 +0x6c fp=0x5401b201d390 sp=0x5401b201d350 pc=0x79d9dc
gvisor.dev/gvisor/pkg/tcpip/link/tun.(*Device).Write(0x5401b1b8b4c0, 0x5401b191c000)
	pkg/tcpip/link/tun/device.go:279 +0x4a4 fp=0x5401b201d540 sp=0x5401b201d390 pc=0x7a0194
gvisor.dev/gvisor/pkg/sentry/devices/tundev.(*tunFD).Write(0x5401b152f808?, {0x107ed00, 0x5401b1b12588}, {{0x10749b8, 0x5401b1ef9008}, {0x0, 0x1, 0x20000200, 0x4a}, {0x0}}, ...)
	pkg/sentry/devices/tundev/tundev.go:176 +0x20c fp=0x5401b201d600 sp=0x5401b201d540 pc=0xa74c2c
gvisor.dev/gvisor/pkg/sentry/vfs.(*FileDescription).Write(0x5401b1b8b450, {0x107ed00, 0x5401b1b12588}, {{0x10749b8, 0x5401b1ef9008}, {0x0, 0x1, 0x20000200, 0x4a}, {0x0}}, ...)
	pkg/sentry/vfs/file_description.go:728 +0x58 fp=0x5401b201d680 sp=0x5401b201d600 pc=0x416a68
gvisor.dev/gvisor/pkg/sentry/syscalls/linux.write(0x5401b1b12588, 0x5401b1b8b450, {{0x10749b8, 0x5401b1ef9008}, {0x0, 0x1, 0x20000200, 0x4a}, {0x0}}, {0x0?})
	pkg/sentry/syscalls/linux/sys_read_write.go:333 +0x70 fp=0x5401b201d800 sp=0x5401b201d680 pc=0x817490
gvisor.dev/gvisor/pkg/sentry/syscalls/linux.Write(0x5401b1b12588, 0xbc?, {{0xc8}, {0x20000200}, {0x4a}, {0x0}, {0x0}, {0x0}})
	pkg/sentry/syscalls/linux/sys_read_write.go:304 +0x100 fp=0x5401b201d940 sp=0x5401b201d800 pc=0x816980
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).executeSyscall(0x5401b1b12588, 0x40, {{0xc8}, {0x20000200}, {0x4a}, {0x0}, {0x0}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:143 +0x4e4 fp=0x5401b201dc80 sp=0x5401b201d940 pc=0x6a25b4
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallInvoke(0x5401b1b12588, 0x40, {{0xc8}, {0x20000200}, {0x4a}, {0x0}, {0x0}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:323 +0x3c fp=0x5401b201dce0 sp=0x5401b201dc80 pc=0x6a33dc
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallEnter(0x5401b1b12588, 0x40, {{0xc8}, {0x20000200}, {0x4a}, {0x0}, {0x0}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:283 +0x58 fp=0x5401b201dd30 sp=0x5401b201dce0 pc=0x6a3108
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscall(0x5401b1d0a820?)
	pkg/sentry/kernel/task_syscall.go:258 +0x238 fp=0x5401b201de10 sp=0x5401b201dd30 pc=0x6a2ec8
gvisor.dev/gvisor/pkg/sentry/kernel.(*runApp).execute(0x5401b1b82360?, 0x5401b1b12588)
	pkg/sentry/kernel/task_run.go:258 +0xd04 fp=0x5401b201df10 sp=0x5401b201de10 pc=0x6993a4
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).run(0x5401b1b12588, 0x58)
	pkg/sentry/kernel/task_run.go:89 +0x1a8 fp=0x5401b201dfb0 sp=0x5401b201df10 pc=0x6981f8
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start.gowrap1()
	pkg/sentry/kernel/task_start.go:531 +0x20 fp=0x5401b201dfd0 sp=0x5401b201dfb0 pc=0x6a1330
runtime.goexit({})
	src/runtime/asm_arm64.s:1447 +0x4 fp=0x5401b201dfd0 sp=0x5401b201dfd0 pc=0x9e984
created by gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start in goroutine 1107
	pkg/sentry/kernel/task_start.go:531 +0xc0