panic: UserChainTarget should never be called.

goroutine 8373 gp=0x647050c8960 m=49 mp=0x64704d03808 [running]:
panic({0x1bd6420?, 0x1f2aea0?})
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/go/src/runtime/panic.go:879 +0x15c fp=0x64705515f00 sp=0x64705515e50 pc=0x9667c
gvisor.dev/gvisor/pkg/tcpip/stack.(*UserChainTarget).Action(...)
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/tcpip/stack/iptables_targets.go:174
gvisor.dev/gvisor/pkg/sentry/socket/netfilter.(*userChainTarget).Action(0x0?, 0x0?, 0x0?, 0x10?, {0x0?, 0x0?})
	<autogenerated>:1 +0x80 fp=0x64705515f20 sp=0x64705515f00 pc=0xebc2c0
gvisor.dev/gvisor/pkg/tcpip/stack.(*IPTables).checkRule(0x2?, 0x1, 0x6470477e6e0, {{0x64704cb1408, 0x4, 0x4}, {0xffffffffffffffff, 0x1, 0x2, 0x0, ...}, ...}, ...)
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/tcpip/stack/iptables.go:774 +0x3d0 fp=0x64705516130 sp=0x64705515f20 pc=0xbedff0
gvisor.dev/gvisor/pkg/tcpip/stack.(*IPTables).checkChain(0x64704e20808, 0x1, 0x6470477e6e0, {{0x64704cb1408, 0x4, 0x4}, {0xffffffffffffffff, 0x1, 0x2, 0x0, ...}, ...}, ...)
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/tcpip/stack/iptables.go:705 +0x16c fp=0x64705516220 sp=0x64705516130 pc=0xbed75c
gvisor.dev/gvisor/pkg/tcpip/stack.(*IPTables).check(0xffffffffffffffff?, {{0x64704cb1408, 0x4, 0x4}, {0xffffffffffffffff, 0x1, 0x2, 0x0, 0xffffffffffffffff}, {0xffffffffffffffff, ...}}, ...)
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/tcpip/stack/iptables.go:650 +0x114 fp=0x647055163f0 sp=0x64705516220 pc=0xbecec4
gvisor.dev/gvisor/pkg/tcpip/stack.check(0x6470477e6e0?, {{0x64704cb1408, 0x4, 0x4}, {0xffffffffffffffff, 0x1, 0x2, 0x0, 0xffffffffffffffff}, {0xffffffffffffffff, ...}}, ...)
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/tcpip/stack/iptables.go:640 +0xc4 fp=0x647055164c0 sp=0x647055163f0 pc=0xbecd64
gvisor.dev/gvisor/pkg/tcpip/stack.(*IPTables).CheckInput(0x64704e20808, 0x6470477e6e0, {0x64705500b28, 0x7})
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/tcpip/stack/iptables.go:459 +0x2b8 fp=0x647055167f0 sp=0x647055164c0 pc=0xbeb8c8
gvisor.dev/gvisor/pkg/tcpip/network/ipv6.(*endpoint).deliverPacketLocally(0x6470437ea88, {0x6470526c80e, 0x28, 0x72}, 0x6470477e6e0, {0x64705500b28?, 0x5?})
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/tcpip/network/ipv6/ipv6.go:1436 +0x168 fp=0x64705516a50 sp=0x647055167f0 pc=0x1027c58
gvisor.dev/gvisor/pkg/tcpip/network/ipv6.(*endpoint).handleValidatedPacket(0x6470437ea88, {0x6470526c80e, 0x28, 0x72}, 0x6470477e6e0, {0x64705500b28, 0x7})
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/tcpip/network/ipv6/ipv6.go:1409 +0xcd8 fp=0x64705516d40 sp=0x64705516a50 pc=0x10271a8
gvisor.dev/gvisor/pkg/tcpip/network/ipv6.(*endpoint).HandlePacket(0x6470437ea88, 0x6470477e6e0)
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/tcpip/network/ipv6/ipv6.go:1195 +0x1d80 fp=0x647055172a0 sp=0x64705516d40 pc=0x1020b10
gvisor.dev/gvisor/pkg/tcpip/stack.(*nic).DeliverNetworkPacket(0x64705544288, 0x86dd, 0x6470477e6e0)
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/tcpip/stack/nic.go:783 +0xa00 fp=0x647055172e0 sp=0x647055172a0 pc=0xc0e7d0
gvisor.dev/gvisor/pkg/tcpip/link/nested.(*Endpoint).DeliverNetworkPacket(0x647044b5348?, 0x86dd, 0x6470477e6e0)
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/tcpip/link/nested/nested.go:61 +0x154 fp=0x64705517320 sp=0x647055172e0 pc=0x1071164
gvisor.dev/gvisor/pkg/tcpip/link/packetsocket.(*Endpoint).DeliverNetworkPacket(0x647042c8f00, 0x86dd, 0x6470477e6e0)
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/tcpip/link/packetsocket/packetsocket.go:50 +0xa4 fp=0x64705517350 sp=0x64705517320 pc=0x1074cb4
gvisor.dev/gvisor/pkg/tcpip/link/channel.(*Endpoint).InjectInbound(0x647042b9140, 0x86dd, 0x6470477e6e0)
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/tcpip/link/channel/channel.go:208 +0x18c fp=0x64705517390 sp=0x64705517350 pc=0x107c8cc
gvisor.dev/gvisor/pkg/tcpip/link/tun.(*Device).Write(0x64705191660, 0x64704f972c0)
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/tcpip/link/tun/device.go:279 +0x17f8 fp=0x64705517540 sp=0x64705517390 pc=0x1083768
gvisor.dev/gvisor/pkg/sentry/devices/tundev.(*tunFD).Write(0x0?, {0x1f588a0, 0x647056c1908}, {{0x1f4def8, 0x64704dde008}, {0x0, 0x1, 0x200003c0, 0x77}, {0x0}}, ...)
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/sentry/devices/tundev/tundev.go:176 +0x828 fp=0x64705517600 sp=0x64705517540 pc=0x1775bb8
gvisor.dev/gvisor/pkg/sentry/vfs.(*FileDescription).Write(0x647051915f0, {0x1f588a0, 0x647056c1908}, {{0x1f4def8, 0x64704dde008}, {0x0, 0x1, 0x200003c0, 0x77}, {0x0}}, ...)
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/sentry/vfs/file_description.go:728 +0x174 fp=0x64705517680 sp=0x64705517600 pc=0x707854
gvisor.dev/gvisor/pkg/sentry/syscalls/linux.write(0x647056c1908, 0x647051915f0, {{0x1f4def8, 0x64704dde008}, {0x0, 0x1, 0x200003c0, 0x77}, {0x0}}, {0x113e09c?})
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/sentry/syscalls/linux/sys_read_write.go:333 +0xdc fp=0x64705517800 sp=0x64705517680 pc=0x11b6cfc
gvisor.dev/gvisor/pkg/sentry/syscalls/linux.Write(0x647056c1908, 0x2f1?, {{0xc8}, {0x200003c0}, {0x77}, {0x0}, {0x0}, {0x0}})
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/sentry/syscalls/linux/sys_read_write.go:304 +0x4c0 fp=0x64705517940 sp=0x64705517800 pc=0x11b5300
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).executeSyscall(0x647056c1908, 0x40, {{0xc8}, {0x200003c0}, {0x77}, {0x0}, {0x0}, {0x0}})
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/sentry/kernel/task_syscall.go:143 +0x1230 fp=0x64705517c80 sp=0x64705517940 pc=0xe08760
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallInvoke(0x647056c1908, 0x40, {{0xc8}, {0x200003c0}, {0x77}, {0x0}, {0x0}, {0x0}})
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/sentry/kernel/task_syscall.go:323 +0xb0 fp=0x64705517ce0 sp=0x64705517c80 pc=0xe0b970
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallEnter(0x647056c1908, 0x40, {{0xc8}, {0x200003c0}, {0x77}, {0x0}, {0x0}, {0x0}})
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/sentry/kernel/task_syscall.go:283 +0x14c fp=0x64705517d30 sp=0x64705517ce0 pc=0xe0a9bc
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscall(0x647051900d0?)
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/sentry/kernel/task_syscall.go:258 +0x8cc fp=0x64705517e10 sp=0x64705517d30 pc=0xe0a18c
gvisor.dev/gvisor/pkg/sentry/kernel.(*runApp).execute(0x647055e1680?, 0x647056c1908)
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/sentry/kernel/task_run.go:258 +0x2fec fp=0x64705517f10 sp=0x64705517e10 pc=0xdeab7c
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).run(0x647056c1908, 0x761)
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/sentry/kernel/task_run.go:89 +0x56c fp=0x64705517fb0 sp=0x64705517f10 pc=0xde728c
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start.gowrap1()
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/sentry/kernel/task_start.go:531 +0x20 fp=0x64705517fd0 sp=0x64705517fb0 pc=0xe04fa0
runtime.goexit({})
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/go/src/runtime/asm_arm64.s:1447 +0x4 fp=0x64705517fd0 sp=0x64705517fd0 pc=0x9ef54
created by gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start in goroutine 8221
	/syzkaller/.cache/bazel/_bazel_root/2defe4792b6e1aac1936903102d81265/sandbox/linux-sandbox/53/execroot/_main/gopath/src/gvisor.dev/gvisor/pkg/sentry/kernel/task_start.go:531 +0x16c