panic: invalid allocation length: 0x0

goroutine 478596 [running]:
gvisor.googlesource.com/gvisor/pkg/sentry/platform/filemem.(*FileMem).Allocate(0xc42028e000, 0x0, 0x3, 0x0, 0x0, 0x0, 0x0)
	pkg/sentry/platform/filemem/filemem.go:232 +0x66f
gvisor.googlesource.com/gvisor/pkg/sentry/fs/tmpfs.(*fileReadWriter).WriteFromBlocks(0xc42060e380, 0x7f4bfd767240, 0xffffffffffffffff, 0x0, 0xf8, 0x0, 0x0, 0x0)
	pkg/sentry/fs/tmpfs/inode_file.go:411 +0x2a8
gvisor.googlesource.com/gvisor/pkg/sentry/safemem.(Writer).WriteFromBlocks-fm(0x7f4bfd767240, 0xffffffffffffffff, 0x0, 0xf8, 0x20000338, 0x7f4bfd767240, 0xffffffffffffffff)
	pkg/sentry/mm/io.go:309 +0x57
gvisor.googlesource.com/gvisor/pkg/sentry/mm.(*MemoryManager).withInternalMappings(0xc42164e000, 0xc730e0, 0xc420188440, 0x20000240, 0x20000338, 0x1, 0xc4206cbc20, 0x10d1d18, 0x2cdb6e9a38a73, 0xc4206cbb68)
	pkg/sentry/mm/io.go:464 +0x72c
gvisor.googlesource.com/gvisor/pkg/sentry/mm.(*MemoryManager).withVecInternalMappings(0xc42164e000, 0xc730e0, 0xc420188440, 0x0, 0x1, 0x20000240, 0xf8, 0xc400000001, 0xc4206cbc20, 0x153bf07462a2cf0d, ...)
	pkg/sentry/mm/io.go:533 +0x7f1
gvisor.googlesource.com/gvisor/pkg/sentry/mm.(*MemoryManager).CopyInTo(0xc42164e000, 0xc730e0, 0xc420188440, 0x0, 0x1, 0x20000240, 0xf8, 0xc65ca0, 0xc42060e380, 0x0, ...)
	pkg/sentry/mm/io.go:309 +0x17c
gvisor.googlesource.com/gvisor/pkg/sentry/usermem.IOSequence.CopyInTo(0xc71940, 0xc42164e000, 0x0, 0x1, 0x20000240, 0xf8, 0x0, 0xc730e0, 0xc420188440, 0xc65ca0, ...)
	pkg/sentry/usermem/usermem.go:528 +0xad
gvisor.googlesource.com/gvisor/pkg/sentry/fs/tmpfs.(*fileInodeOperations).write(0xc421ade900, 0xc730e0, 0xc420188440, 0xc71940, 0xc42164e000, 0x0, 0x1, 0x20000240, 0xf8, 0x0, ...)
	pkg/sentry/fs/tmpfs/inode_file.go:289 +0x198
gvisor.googlesource.com/gvisor/pkg/sentry/fs/tmpfs.(*regularFileOperations).Write(0xc42041a268, 0xc730e0, 0xc420188440, 0xc421b973b0, 0xc71940, 0xc42164e000, 0x0, 0x1, 0x20000240, 0xf8, ...)
	pkg/sentry/fs/tmpfs/file_regular.go:50 +0x89
gvisor.googlesource.com/gvisor/pkg/sentry/fs.(*File).Pwritev(0xc421b973b0, 0xc730e0, 0xc420188440, 0xc71940, 0xc42164e000, 0x0, 0x1, 0x20000240, 0xf8, 0x0, ...)
	pkg/sentry/fs/file.go:294 +0x1c5
gvisor.googlesource.com/gvisor/pkg/sentry/syscalls/linux.performCallback(0xc420d9f600, 0xc421b973b0, 0x200003c0, 0xc420164700, 0xc71940, 0xc42164e000, 0x0, 0x1, 0x20000240, 0xf8, ...)
	pkg/sentry/syscalls/linux/sys_aio.go:264 +0x2a7
gvisor.googlesource.com/gvisor/pkg/sentry/syscalls/linux.submitCallback.func1()
	pkg/sentry/syscalls/linux/sys_aio.go:342 +0x7c
gvisor.googlesource.com/gvisor/pkg/sentry/fs.Async.func1(0xc4203753b0)
	pkg/sentry/fs/fs.go:82 +0x4f
created by gvisor.googlesource.com/gvisor/pkg/sentry/fs.Async
	pkg/sentry/fs/fs.go:80 +0x58