syzbot

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x1f2b6c6]

goroutine 1364 [running]:
panic({0x322fc0, 0x28ac300})
	GOROOT/src/runtime/panic.go:987 +0x3bb fp=0xc000b20330 sp=0xc000b20270 pc=0x127993b
runtime.panicmem(...)
	GOROOT/src/runtime/panic.go:260
runtime.sigpanic()
	GOROOT/src/runtime/signal_unix.go:837 +0x37d fp=0xc000b20390 sp=0xc000b20330 pc=0x129281d
gvisor.dev/gvisor/pkg/sentry/inet.(*Namespace).Stack(...)
	pkg/sentry/inet/namespace.go:108
gvisor.dev/gvisor/pkg/sentry/fsimpl/proc.(*filesystem).newTaskNetDir(0xc00028b360, {0x786da0, 0xc001269500}, 0xc0013e8a80)
	pkg/sentry/fsimpl/proc/task_net.go:46 +0x166 fp=0xc000b205d0 sp=0xc000b20390 pc=0x1f2b6c6
gvisor.dev/gvisor/pkg/sentry/fsimpl/proc.(*filesystem).newTaskInode(0xc00028b360, {0x786da0, 0xc001269500}, 0xc0013e8a80, 0xc0002841c0, 0x1, 0x0)
	pkg/sentry/fsimpl/proc/task.go:73 +0x136d fp=0xc000b20960 sp=0xc000b205d0 pc=0x1f16ced
gvisor.dev/gvisor/pkg/sentry/fsimpl/proc.(*tasksInode).Lookup(0xc001053400, {0x786da0, 0xc001269500}, {0xc000ac6e10, 0x2})
	pkg/sentry/fsimpl/proc/tasks.go:130 +0x3e5 fp=0xc000b20a10 sp=0xc000b20960 pc=0x1f34165
gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs.(*Filesystem).revalidateChildLocked(0x313680?, {0x786da0, 0xc001269500}, 0x2?, 0xc000b68ab0, {0xc000ac6e10, 0x2}, 0x0)
	pkg/sentry/fsimpl/kernfs/filesystem.go:131 +0x289 fp=0xc000b20ab8 sp=0xc000b20a10 pc=0x18d8c69
gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs.(*Filesystem).stepExistingLocked(0xc0013fb200?, {0x786da0, 0xc001269500}, 0xc0013fb200, 0xc000b68ab0)
	pkg/sentry/fsimpl/kernfs/filesystem.go:75 +0x525 fp=0xc000b20c08 sp=0xc000b20ab8 pc=0x18d84c5
gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs.(*Filesystem).walkExistingLocked(0xc00028b3b0?, {0x786da0, 0xc001269500}, 0xc0013fb200)
	pkg/sentry/fsimpl/kernfs/filesystem.go:163 +0x11b fp=0xc000b20c70 sp=0xc000b20c08 pc=0x18d8ffb
gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs.(*Filesystem).OpenAt(0xc00028b360, {0x786da0, 0xc001269500}, 0xc0013fb200, {0x8002, 0x0, 0x0})
	pkg/sentry/fsimpl/kernfs/filesystem.go:486 +0x18d fp=0xc000b20f88 sp=0xc000b20c70 pc=0x18dda6d
gvisor.dev/gvisor/pkg/sentry/fsimpl/proc.(*filesystem).OpenAt(0xc00028b360, {0x786da0, 0xc001269500}, 0xc0013fb200?, {0x39c3480?, 0x0?, 0x0?})
	<autogenerated>:1 +0x85 fp=0xc000b20fe8 sp=0xc000b20f88 pc=0x1f59005
gvisor.dev/gvisor/pkg/sentry/vfs.(*VirtualFilesystem).OpenAt(0xc00074cd40?, {0x786da0, 0xc001269500}, 0xc0006bf200?, 0xc000b21428, 0xc000b212f8)
	pkg/sentry/vfs/vfs.go:460 +0x6bc fp=0xc000b21250 sp=0xc000b20fe8 pc=0x18260dc
gvisor.dev/gvisor/pkg/sentry/syscalls/linux.openat(0xc001269500, 0x28c81c4?, 0x1?, 0x2, 0x0)
	pkg/sentry/syscalls/linux/sys_file.go:112 +0x365 fp=0xc000b214d8 sp=0xc000b21250 pc=0x1de0705
gvisor.dev/gvisor/pkg/sentry/syscalls/linux.Openat(0x0?, 0xc000b215d0?, {{0xffffff9c}, {0x7f28c6421bd0}, {0x2}, {0x0}, {0x12}, {0x7f28c6421906}})
	pkg/sentry/syscalls/linux/sys_file.go:91 +0xcb fp=0xc000b21550 sp=0xc000b214d8 pc=0x1de022b
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).executeSyscall(0xc001269500, 0x101, {{0xffffff9c}, {0x7f28c6421bd0}, {0x2}, {0x0}, {0x12}, {0x7f28c6421906}})
	pkg/sentry/kernel/task_syscall.go:142 +0xabf fp=0xc000b21968 sp=0xc000b21550 pc=0x1bc661f
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallInvoke(0xc001269500, 0x1?, {{0xffffff9c}, {0x7f28c6421bd0}, {0x2}, {0x0}, {0x12}, {0x7f28c6421906}})
	pkg/sentry/kernel/task_syscall.go:322 +0x8e fp=0xc000b21a08 sp=0xc000b21968 pc=0x1bc872e
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallEnter(0xc000022870?, 0xc000b21b37?, {{0xffffff9c}, {0x7f28c6421bd0}, {0x2}, {0x0}, {0x12}, {0x7f28c6421906}})
	pkg/sentry/kernel/task_syscall.go:282 +0xc5 fp=0xc000b21a80 sp=0xc000b21a08 pc=0x1bc8025
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscall(0xc001269500)
	pkg/sentry/kernel/task_syscall.go:257 +0x53b fp=0xc000b21ba8 sp=0xc000b21a80 pc=0x1bc7b3b
gvisor.dev/gvisor/pkg/sentry/kernel.(*runApp).execute(0xc001269500?, 0xc001269500)
	pkg/sentry/kernel/task_run.go:269 +0x22b4 fp=0xc000b21e68 sp=0xc000b21ba8 pc=0x1bb0534
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).run(0xc001269500, 0x30)
	pkg/sentry/kernel/task_run.go:98 +0x35b fp=0xc000b21fb0 sp=0xc000b21e68 pc=0x1bad81b
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start.func1()
	pkg/sentry/kernel/task_start.go:389 +0x48 fp=0xc000b21fe0 sp=0xc000b21fb0 pc=0x1bc3d08
runtime.goexit()
	src/runtime/asm_amd64.s:1598 +0x1 fp=0xc000b21fe8 sp=0xc000b21fe0 pc=0x12b28c1
created by gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start
	pkg/sentry/kernel/task_start.go:389 +0x1da