panic: runtime error: index out of range [-1]

goroutine 248 [running]:
panic({0x12c50c0, 0xc000c12270})
	GOROOT/src/runtime/panic.go:1147 +0x3a8 fp=0xc0009b32b8 sp=0xc0009b31f8 pc=0x435148
runtime.goPanicIndex(0xffffffffffffffff, 0x0)
	GOROOT/src/runtime/panic.go:90 +0x75 fp=0xc0009b32f8 sp=0xc0009b32b8 pc=0x4324d5
gvisor.dev/gvisor/pkg/sentry/fsimpl/tmpfs.parseSize({0x0, 0xc000b1e450})
	pkg/sentry/fsimpl/tmpfs/tmpfs.go:951 +0x194 fp=0xc0009b3330 sp=0xc0009b32f8 pc=0x94d1f4
gvisor.dev/gvisor/pkg/sentry/fsimpl/tmpfs.FilesystemType.GetFilesystem({}, {0x15a9660, 0xc000893500}, 0xc0005a8ca8, 0xc000a162a0, {0xc0005a21f0, 0xc0009b35e8}, {{0xc000548800, 0x4}, {0x0, ...}})
	pkg/sentry/fsimpl/tmpfs/tmpfs.go:205 +0x6c5 fp=0xc0009b35b0 sp=0xc0009b3330 pc=0x949125
gvisor.dev/gvisor/pkg/sentry/fsimpl/tmpfs.(*FilesystemType).GetFilesystem(0x21dd9c0, {0x15a9660, 0xc000893500}, 0xc0009b3668, 0xc0009b3668, {0xc000548600, 0xc000735800}, {{0xc000548800, 0x4}, {0x0, ...}})
	<autogenerated>:1 +0x8c fp=0xc0009b3610 sp=0xc0009b35b0 pc=0x95398c
gvisor.dev/gvisor/pkg/sentry/vfs.(*VirtualFilesystem).MountDisconnected(0x0, {0x15a9660, 0xc000893500}, 0xc000735800, {0xc000548600, 0x8}, {0xc000548500, 0xc0009b3738}, 0xc0009b3888)
	pkg/sentry/vfs/mount.go:200 +0xf7 fp=0xc0009b3688 sp=0xc0009b3610 pc=0x7af537
gvisor.dev/gvisor/pkg/sentry/vfs.(*VirtualFilesystem).MountAt(0xc0002a3b00, {0x15a9660, 0xc000893500}, 0xc000548700, {0xc000548600, 0x1}, 0x0, {0xc000548500, 0x1}, 0xc0009b3888)
	pkg/sentry/vfs/mount.go:272 +0x95 fp=0xc0009b3748 sp=0xc0009b3688 pc=0x7afad5
gvisor.dev/gvisor/pkg/sentry/syscalls/linux/vfs2.Mount(0xc000893500, {{0x20003d40}, {0x20003d80}, {0x20003dc0}, {0x0}, {0x20003e00}, {0x0}})
	pkg/sentry/syscalls/linux/vfs2/mount.go:112 +0x5cd fp=0xc0009b3970 sp=0xc0009b3748 pc=0xf06a6d
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).executeSyscall(0xc000893500, 0xa5, {{0x20003d40}, {0x20003d80}, {0x20003dc0}, {0x0}, {0x20003e00}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:142 +0x7db fp=0xc0009b3cb8 sp=0xc0009b3970 pc=0xa48adb
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallInvoke(0xc000893500, 0x0, {{0x20003d40}, {0x20003d80}, {0x20003dc0}, {0x0}, {0x20003e00}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:322 +0x57 fp=0xc0009b3d28 sp=0xc0009b3cb8 pc=0xa4a0d7
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallEnter(0xc00040f2c0, 0xc00082f860, {{0x20003d40}, {0x20003d80}, {0x20003dc0}, {0x0}, {0x20003e00}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:282 +0x85 fp=0xc0009b3d88 sp=0xc0009b3d28 pc=0xa49ca5
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscall(0xc000893500)
	pkg/sentry/kernel/task_syscall.go:257 +0x3a5 fp=0xc0009b3e50 sp=0xc0009b3d88 pc=0xa49965
gvisor.dev/gvisor/pkg/sentry/kernel.(*runApp).execute(0xc0005c2080, 0xc000893500)
	pkg/sentry/kernel/task_run.go:247 +0x114a fp=0xc0009b3f70 sp=0xc0009b3e50 pc=0xa3b6ca
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).run(0xc000893500)
	pkg/sentry/kernel/task_run.go:90 +0x1ec fp=0xc0009b3fc8 sp=0xc0009b3f70 pc=0xa39eec
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start·dwrap·239()
	pkg/sentry/kernel/task_start.go:363 +0x26 fp=0xc0009b3fe0 sp=0xc0009b3fc8 pc=0xa46f26
runtime.goexit()
	src/runtime/asm_amd64.s:1581 +0x1 fp=0xc0009b3fe8 sp=0xc0009b3fe0 pc=0x4692a1
created by gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start
	pkg/sentry/kernel/task_start.go:363 +0xf5