syzbot

panic: runtime error: index out of range [1] with length 1

goroutine 269322 [running]:
panic(0xef1480, 0xc00050e320)
	GOROOT/src/runtime/panic.go:1064 +0x46d fp=0xc0035a5238 sp=0xc0035a5180 pc=0x43432d
runtime.goPanicIndex(0x1, 0x1)
	GOROOT/src/runtime/panic.go:88 +0xa3 fp=0xc0035a5280 sp=0xc0035a5238 pc=0x432023
gvisor.dev/gvisor/pkg/sentry/pgalloc.(*MemoryFile).forEachMappingSlice(0xc0003a2000, 0x7efe0000, 0x7f000000, 0xc0035a5388, 0x16, 0xc0029a6000)
	pkg/sentry/pgalloc/pgalloc.go:662 +0x293 fp=0xc0035a5318 sp=0xc0035a5280 pc=0x6c4d43
gvisor.dev/gvisor/pkg/sentry/pgalloc.(*MemoryFile).MapInternal(0xc0003a2000, 0x7efe0000, 0x7f000000, 0x2b6f74000101, 0xc003148080, 0xd, 0x2b6f74ad7000, 0x2b6f74ad8000, 0xc001000100, 0xc003148800)
	pkg/sentry/pgalloc/pgalloc.go:644 +0xd3 fp=0xc0035a53f0 sp=0xc0035a5318 pc=0x6c4803
gvisor.dev/gvisor/pkg/sentry/mm.pmaIterator.getInternalMappingsLocked(0xc003148800, 0xb, 0x0, 0x0)
	pkg/sentry/mm/pma.go:1006 +0xcb fp=0xc0035a5458 sp=0xc0035a53f0 pc=0x82192b
gvisor.dev/gvisor/pkg/sentry/mm.(*MemoryManager).getPMAInternalMappingsLocked(0xc003148000, 0xc003148800, 0xb, 0x2b6f74ad79d0, 0x2b6f74ad79d4, 0x2b6f74ad7000, 0x2b6f74ad79d4, 0x100, 0xc003148800)
	pkg/sentry/mm/pma.go:772 +0x5d fp=0xc0035a54b8 sp=0xc0035a5458 pc=0x82019d
gvisor.dev/gvisor/pkg/sentry/mm.(*MemoryManager).withInternalMappings(0xc003148000, 0x113a040, 0xc002b74000, 0x2b6f74ad79d0, 0x2b6f74ad79d4, 0x161630a700000100, 0xc0035a5608, 0x0, 0xc00141819c, 0x8)
	pkg/sentry/mm/io.go:532 +0x357 fp=0xc0035a55b8 sp=0xc0035a54b8 pc=0x817e97
gvisor.dev/gvisor/pkg/sentry/mm.(*MemoryManager).CopyOut(0xc003148000, 0x113a040, 0xc002b74000, 0x2b6f74ad79d0, 0xc00141819c, 0x4, 0x4, 0x100, 0x4, 0xe321a0, ...)
	pkg/sentry/mm/io.go:119 +0x12d fp=0xc0035a5648 sp=0xc0035a55b8 pc=0x81571d
gvisor.dev/gvisor/pkg/usermem.(*IOReadWriter).Write(0xc0035a5708, 0xc00141819c, 0x4, 0x4, 0x18cf5c0, 0xe321a0, 0xc001418198)
	pkg/usermem/usermem.go:165 +0x87 fp=0xc0035a56b0 sp=0xc0035a5648 pc=0x5ae7b7
gvisor.dev/gvisor/pkg/usermem.CopyObjectOut(0x113a040, 0xc002b74000, 0x1133540, 0xc003148000, 0x2b6f74ad79d0, 0xe321a0, 0xc001418198, 0x100, 0xdf39e0, 0xc0027fa400, ...)
	pkg/usermem/usermem.go:198 +0x160 fp=0xc0035a5748 sp=0xc0035a56b0 pc=0x5ae990
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).CopyOut(0xc002b74000, 0x2b6f74ad79d0, 0xe321a0, 0xc001418198, 0x0, 0xc000778340, 0x0)
	pkg/sentry/kernel/task_usermem.go:73 +0x7b fp=0xc0035a57b0 sp=0xc0035a5748 pc=0x898c5b
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Clone(0xc002b74000, 0xc0035a5a78, 0xc000000000, 0x0, 0x0, 0x0)
	pkg/sentry/kernel/task_clone.go:345 +0xca2 fp=0xc0035a5a48 sp=0xc0035a57b0 pc=0x87e632
gvisor.dev/gvisor/pkg/sentry/syscalls/linux.clone(0xc002b74000, 0x3d0f00, 0x2b6f74ad6db0, 0x2b6f74ad79d0, 0x2b6f74ad79d0, 0x2b6f74ad7700, 0x43e4a8, 0xc002b63b00, 0x200000003, 0xc002b63b00)
	pkg/sentry/syscalls/linux/sys_thread.go:226 +0x15b fp=0xc0035a5ae0 sp=0xc0035a5a48 pc=0x90a85b
gvisor.dev/gvisor/pkg/sentry/syscalls/linux.Clone(0xc002b74000, 0x3d0f00, 0x2b6f74ad6db0, 0x2b6f74ad79d0, 0x2b6f74ad79d0, 0x2b6f74ad7700, 0x2b6f74ad7700, 0x0, 0x0, 0x3e08, ...)
	pkg/sentry/syscalls/linux/sys_clone_amd64.go:34 +0x67 fp=0xc0035a5b40 sp=0xc0035a5ae0 pc=0x8df867
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).executeSyscall(0xc002b74000, 0x38, 0x3d0f00, 0x2b6f74ad6db0, 0x2b6f74ad79d0, 0x2b6f74ad79d0, 0x2b6f74ad7700, 0x2b6f74ad7700, 0x0, 0xfa0640, ...)
	pkg/sentry/kernel/task_syscall.go:170 +0x122 fp=0xc0035a5ca0 sp=0xc0035a5b40 pc=0x895d82
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallInvoke(0xc002b74000, 0x38, 0x3d0f00, 0x2b6f74ad6db0, 0x2b6f74ad79d0, 0x2b6f74ad79d0, 0x2b6f74ad7700, 0x2b6f74ad7700, 0x2b6f74ad7700, 0x2b6f74ad7700)
	pkg/sentry/kernel/task_syscall.go:305 +0x66 fp=0xc0035a5d28 sp=0xc0035a5ca0 pc=0x896f66
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallEnter(0xc002b74000, 0x38, 0x3d0f00, 0x2b6f74ad6db0, 0x2b6f74ad79d0, 0x2b6f74ad79d0, 0x2b6f74ad7700, 0x2b6f74ad7700, 0xc001d0e360, 0x1)
	pkg/sentry/kernel/task_syscall.go:265 +0x96 fp=0xc0035a5d88 sp=0xc0035a5d28 pc=0x896af6
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscall(0xc002b74000, 0x2, 0xc0007791c0)
	pkg/sentry/kernel/task_syscall.go:240 +0x15c fp=0xc0035a5e48 sp=0xc0035a5d88 pc=0x89648c
gvisor.dev/gvisor/pkg/sentry/kernel.(*runApp).execute(0x0, 0xc002b74000, 0x1117ca0, 0x0)
	pkg/sentry/kernel/task_run.go:259 +0xec8 fp=0xc0035a5f60 sp=0xc0035a5e48 pc=0x88b598
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).run(0xc002b74000, 0x2620)
	pkg/sentry/kernel/task_run.go:92 +0x18b fp=0xc0035a5fd0 sp=0xc0035a5f60 pc=0x889fbb
runtime.goexit()
	src/runtime/asm_amd64.s:1373 +0x1 fp=0xc0035a5fd8 sp=0xc0035a5fd0 pc=0x467d01
created by gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start
	pkg/sentry/kernel/task_start.go:318 +0xfe