panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x8 pc=0x91d130]

goroutine 226 [running]:
panic({0x10ec200, 0x1e68c20})
	GOROOT/src/runtime/panic.go:987 +0x3bb fp=0xc000b8ef90 sp=0xc000b8eed0 pc=0x436c1b
runtime.panicmem(...)
	GOROOT/src/runtime/panic.go:260
runtime.sigpanic()
	GOROOT/src/runtime/signal_unix.go:837 +0x37d fp=0xc000b8eff0 sp=0xc000b8ef90 pc=0x44e23d
gvisor.dev/gvisor/pkg/sentry/kernel.(*ProcessGroup).SendSignal(0x0, 0xc000b8f1e0)
	pkg/sentry/kernel/sessions.go:237 +0x50 fp=0xc000b8f0e0 sp=0xc000b8eff0 pc=0x91d130
gvisor.dev/gvisor/pkg/sentry/fsimpl/devpts.(*inputQueueTransformer).transform(0x7f5, 0xc000002180, 0xc000002190, {0xc000b14000?, 0xc0003c0020?, 0x0?})
	pkg/sentry/fsimpl/devpts/line_discipline.go:402 +0x2eb fp=0xc000b8f308 sp=0xc000b8f0e0 pc=0xc8946b
gvisor.dev/gvisor/pkg/sentry/fsimpl/devpts.(*queue).pushWaitBufLocked(0xc000002190, 0xc0009c8000?)
	pkg/sentry/fsimpl/devpts/queue.go:219 +0x99 fp=0xc000b8f370 sp=0xc000b8f308 pc=0xc8bd79
gvisor.dev/gvisor/pkg/sentry/fsimpl/devpts.(*queue).write(0xc000002190, {0x14c8ed8, 0xc0009f0000}, {{0x14c3190, 0xc0009c8000}, {0x0, 0x1, 0x200003c0, 0x7f5}, {0x0, ...}}, ...)
	pkg/sentry/fsimpl/devpts/queue.go:183 +0x214 fp=0xc000b8f450 sp=0xc000b8f370 pc=0xc8b734
gvisor.dev/gvisor/pkg/sentry/fsimpl/devpts.(*lineDiscipline).inputQueueWrite(0xc000002180, {0x14c8ed8?, 0xc0009f0000?}, {{0x14c3190, 0xc0009c8000}, {0x0, 0x1, 0x200003c0, 0x7f5}, {0x0, ...}})
	pkg/sentry/fsimpl/devpts/line_discipline.go:217 +0xbf fp=0xc000b8f4d8 sp=0xc000b8f450 pc=0xc8863f
gvisor.dev/gvisor/pkg/sentry/fsimpl/devpts.(*masterFileDescription).Write(0xc00038c030?, {0x14c8ed8?, 0xc0009f0000?}, {{0x14c3190, 0xc0009c8000}, {0x0, 0x1, 0x200003c0, 0x7f5}, {0x0, ...}}, ...)
	pkg/sentry/fsimpl/devpts/master.go:134 +0x5b fp=0xc000b8f538 sp=0xc000b8f4d8 pc=0xc8a0fb
gvisor.dev/gvisor/pkg/sentry/vfs.(*FileDescription).Write(0xc0005b4400, {0x14c8ed8, 0xc0009f0000}, {{0x14c3190, 0xc0009c8000}, {0x0, 0x1, 0x200003c0, 0x7f5}, {0x0, ...}}, ...)
	pkg/sentry/vfs/file_description.go:674 +0x91 fp=0xc000b8f5b8 sp=0xc000b8f538 pc=0x73fa31
gvisor.dev/gvisor/pkg/sentry/syscalls/linux.write(0x8?, 0xc0005b4400, {{0x14c3190, 0xc0009c8000}, {0x0, 0x1, 0x200003c0, 0x7f5}, {0x0, 0x1}}, ...)
	pkg/sentry/syscalls/linux/sys_read_write.go:347 +0x85 fp=0xc000b8f778 sp=0xc000b8f5b8 pc=0xa85c65
gvisor.dev/gvisor/pkg/sentry/syscalls/linux.Write(0xc0009f0000, {{0x3}, {0x200003c0}, {0x7f5}, {0x0}, {0x0}, {0x0}})
	pkg/sentry/syscalls/linux/sys_read_write.go:316 +0x1c5 fp=0xc000b8f880 sp=0xc000b8f778 pc=0xa85545
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).executeSyscall(0xc0009f0000, 0x1, {{0x3}, {0x200003c0}, {0x7f5}, {0x0}, {0x0}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:142 +0x755 fp=0xc000b8fc70 sp=0xc000b8f880 pc=0x942635
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallInvoke(0xc0009f0000, 0x0?, {{0x3}, {0x200003c0}, {0x7f5}, {0x0}, {0x0}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:322 +0x4a fp=0xc000b8fcd0 sp=0xc000b8fc70 pc=0x94386a
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallEnter(0xc00003f8c0?, 0xc000b8fe18?, {{0x3}, {0x200003c0}, {0x7f5}, {0x0}, {0x0}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:282 +0x65 fp=0xc000b8fd30 sp=0xc000b8fcd0 pc=0x943545
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscall(0xc0009f2000?)
	pkg/sentry/kernel/task_syscall.go:257 +0x2f0 fp=0xc000b8fe28 sp=0xc000b8fd30 pc=0x9432b0
gvisor.dev/gvisor/pkg/sentry/kernel.(*runApp).execute(0xc0000e6b80?, 0xc0009f0000)
	pkg/sentry/kernel/task_run.go:265 +0x103e fp=0xc000b8ff60 sp=0xc000b8fe28 pc=0x9374de
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).run(0xc0009f0000, 0x19)
	pkg/sentry/kernel/task_run.go:94 +0x1b8 fp=0xc000b8ffc0 sp=0xc000b8ff60 pc=0x935e78
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start.func1()
	pkg/sentry/kernel/task_start.go:377 +0x2a fp=0xc000b8ffe0 sp=0xc000b8ffc0 pc=0x940e2a
runtime.goexit()
	src/runtime/asm_amd64.s:1598 +0x1 fp=0xc000b8ffe8 sp=0xc000b8ffe0 pc=0x46d5e1
created by gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start
	pkg/sentry/kernel/task_start.go:377 +0xef