syzbot

panic: invalid allocation length: 0x0

goroutine 363450 gp=0xc001baefc0 m=27 mp=0xc0003ee308 [running]:
panic({0x114b520?, 0xc002f02ce0?})
	bazel-out/k8-fastbuild/bin/external/io_bazel_rules_go/stdlib_/src/runtime/panic.go:804 +0x168 fp=0xc000cbd550 sp=0xc000cbd4a0 pc=0x4740c8
gvisor.dev/gvisor/pkg/sentry/pgalloc.(*MemoryFile).Allocate(0x20eda80?, 0x114e160?, {0x1, 0x6, 0x0, 0x0, 0x0, 0x0})
	pkg/sentry/pgalloc/pgalloc.go:639 +0x6f9 fp=0xc000cbd6a0 sp=0xc000cbd550 pc=0x83ab59
gvisor.dev/gvisor/pkg/sentry/socket/netstack/packetmmap.(*ringBuffer).init(0xc0030a0010, {0x15cd040, 0xc00474ec88}, 0xc0029f4fc0)
	pkg/sentry/socket/netstack/packetmmap/ring_buffer.go:78 +0x2a8 fp=0xc000cbd768 sp=0xc000cbd6a0 pc=0xae3948
gvisor.dev/gvisor/pkg/sentry/socket/netstack/packetmmap.(*Endpoint).Init(0xc00023a400?, {0x15cd040?, 0xc00474ec88?}, {0xc0029f4fc0, 0x1, 0x1, 0xc004260808, 0xc00023a4f0, 0xc003e5acc0, 0x0, ...})
	pkg/sentry/socket/netstack/packetmmap/endpoint.go:128 +0x265 fp=0xc000cbd7b8 sp=0xc000cbd768 pc=0xae14a5
gvisor.dev/gvisor/pkg/sentry/socket/netstack.setSockOptPacket(0xc00474ec88, {0xc000cbd8e0?, 0x40e7ff?}, {0x7f3adf4d0340, 0xc00023a400}, 0xc000cbd901?, {0xc00474f79c?, 0xc000cbd908?, 0xc001f3c008?})
	pkg/sentry/socket/netstack/netstack.go:2745 +0x315 fp=0xc000cbd898 sp=0xc000cbd7b8 pc=0xba52f5
gvisor.dev/gvisor/pkg/sentry/socket/netstack.SetSockOpt(0x8dcbc0?, {0x15df0d8?, 0xc000b15180?}, {0x7f3adf4d0340?, 0xc00023a400?}, 0xc00474ec88?, 0xc000cbd988?, {0xc00474f79c, 0x1c, 0x90})
	pkg/sentry/socket/netstack/netstack.go:1873 +0x148 fp=0xc000cbd8f0 sp=0xc000cbd898 pc=0xba2468
gvisor.dev/gvisor/pkg/sentry/socket/netstack.(*sock).SetSockOpt(0xc000b15180, 0xc00474ec88?, 0x107?, 0x5?, {0xc00474f79c, 0x1c?, 0x90?})
	pkg/sentry/socket/netstack/netstack.go:634 +0x225 fp=0xc000cbd998 sp=0xc000cbd8f0 pc=0xb9c8e5
gvisor.dev/gvisor/pkg/sentry/syscalls/linux.SetSockOpt(0xc00474ec88, 0x10?, {{0x4}, {0x107}, {0x5}, {0x200000000100}, {0x1c}, {0x0}})
	pkg/sentry/syscalls/linux/sys_socket.go:551 +0x246 fp=0xc000cbda78 sp=0xc000cbd998 pc=0xc2a546
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).executeSyscall(0xc00474ec88, 0x36, {{0x4}, {0x107}, {0x5}, {0x200000000100}, {0x1c}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:143 +0x657 fp=0xc000cbdca8 sp=0xc000cbda78 pc=0xa777f7
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallInvoke(0xc00474ec88, 0x36, {{0x4}, {0x107}, {0x5}, {0x200000000100}, {0x1c}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:323 +0x45 fp=0xc000cbdd00 sp=0xc000cbdca8 pc=0xa78965
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallEnter(0xc00474ec88, 0x36, {{0x4}, {0x107}, {0x5}, {0x200000000100}, {0x1c}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:283 +0x65 fp=0xc000cbdd50 sp=0xc000cbdd00 pc=0xa78665
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscall(0xc004286580?)
	pkg/sentry/kernel/task_syscall.go:258 +0x2a5 fp=0xc000cbde28 sp=0xc000cbdd50 pc=0xa783e5
gvisor.dev/gvisor/pkg/sentry/kernel.(*runApp).execute(0xc0060a9b00?, 0xc00474ec88)
	pkg/sentry/kernel/task_run.go:269 +0xf17 fp=0xc000cbdf30 sp=0xc000cbde28 pc=0xa6dbd7
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).run(0xc00474ec88, 0xc55a)
	pkg/sentry/kernel/task_run.go:97 +0x214 fp=0xc000cbdfc0 sp=0xc000cbdf30 pc=0xa6c634
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start.gowrap1()
	pkg/sentry/kernel/task_start.go:412 +0x25 fp=0xc000cbdfe0 sp=0xc000cbdfc0 pc=0xa76205
runtime.goexit({})
	src/runtime/asm_amd64.s:1700 +0x1 fp=0xc000cbdfe8 sp=0xc000cbdfe0 pc=0x47d1a1
created by gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start in goroutine 363463
	pkg/sentry/kernel/task_start.go:412 +0xc5