panic: invalid allocation length: 0x0

goroutine 408630 [running]:
gvisor.googlesource.com/gvisor/pkg/sentry/platform/filemem.(*FileMem).Allocate(0xc42015db00, 0x0, 0x3, 0x0, 0x0, 0x0, 0x0)
	pkg/sentry/platform/filemem/filemem.go:232 +0x765
gvisor.googlesource.com/gvisor/pkg/sentry/fs/tmpfs.(*fileReadWriter).WriteFromBlocks(0xc4201fc340, 0x7f7d79c00140, 0xffffffffffffffff, 0x0, 0x95, 0x0, 0x0, 0x0)
	pkg/sentry/fs/tmpfs/inode_file.go:411 +0x461
gvisor.googlesource.com/gvisor/pkg/sentry/safemem.(Writer).WriteFromBlocks-fm(0x7f7d79c00140, 0xffffffffffffffff, 0x0, 0x95, 0x200001d5, 0x7f7d79c00140, 0xffffffffffffffff)
	pkg/sentry/mm/io.go:309 +0x76
gvisor.googlesource.com/gvisor/pkg/sentry/mm.(*MemoryManager).withInternalMappings(0xc42124a000, 0x10d3f40, 0xc420388268, 0x20000140, 0x200001d5, 0x1, 0xc421b69b68, 0xc421b69968, 0x47b965, 0x47ed19)
	pkg/sentry/mm/io.go:464 +0x88f
gvisor.googlesource.com/gvisor/pkg/sentry/mm.(*MemoryManager).withVecInternalMappings(0xc42124a000, 0x10d3f40, 0xc420388268, 0x0, 0x1, 0x20000140, 0x95, 0x1, 0xc421b69b68, 0x0, ...)
	pkg/sentry/mm/io.go:533 +0x974
gvisor.googlesource.com/gvisor/pkg/sentry/mm.(*MemoryManager).CopyInTo(0xc42124a000, 0x10d3f40, 0xc420388268, 0x0, 0x1, 0x20000140, 0x95, 0x10c4a60, 0xc4201fc340, 0x153c6872ed2c0000, ...)
	pkg/sentry/mm/io.go:309 +0x211
gvisor.googlesource.com/gvisor/pkg/sentry/usermem.IOSequence.CopyInTo(0x10d2620, 0xc42124a000, 0x0, 0x1, 0x20000140, 0x95, 0x0, 0x10d3f40, 0xc420388268, 0x10c4a60, ...)
	pkg/sentry/usermem/usermem.go:528 +0xcf
gvisor.googlesource.com/gvisor/pkg/sentry/fs/tmpfs.(*fileInodeOperations).write(0xc4217538c0, 0x10d3f40, 0xc420388268, 0x10d2620, 0xc42124a000, 0x0, 0x1, 0x20000140, 0x95, 0x0, ...)
	pkg/sentry/fs/tmpfs/inode_file.go:289 +0x1cb
gvisor.googlesource.com/gvisor/pkg/sentry/fs/tmpfs.(*regularFileOperations).Write(0xc4211a6060, 0x10d3f40, 0xc420388268, 0xc421027170, 0x10d2620, 0xc42124a000, 0x0, 0x1, 0x20000140, 0x95, ...)
	pkg/sentry/fs/tmpfs/file_regular.go:50 +0xb9
gvisor.googlesource.com/gvisor/pkg/sentry/fs.(*File).Pwritev(0xc421027170, 0x10d3f40, 0xc420388268, 0x10d2620, 0xc42124a000, 0x0, 0x1, 0x20000140, 0x95, 0x0, ...)
	pkg/sentry/fs/file.go:294 +0x200
gvisor.googlesource.com/gvisor/pkg/sentry/syscalls/linux.performCallback(0xc421901200, 0xc421027170, 0x200000c0, 0xc421176300, 0x10d2620, 0xc42124a000, 0x0, 0x1, 0x20000140, 0x95, ...)
	pkg/sentry/syscalls/linux/sys_aio.go:264 +0x457
gvisor.googlesource.com/gvisor/pkg/sentry/syscalls/linux.submitCallback.func1()
	pkg/sentry/syscalls/linux/sys_aio.go:342 +0x11b
gvisor.googlesource.com/gvisor/pkg/sentry/fs.Async.func1(0xc4211f2770)
	pkg/sentry/fs/fs.go:82 +0x5d
created by gvisor.googlesource.com/gvisor/pkg/sentry/fs.Async
	pkg/sentry/fs/fs.go:80 +0x66