From ecff24930cb2dd5b0910da859d6e712f2f1d32c4 Mon Sep 17 00:00:00 2001 From: Jamie Liu Date: Tue, 9 Jun 2020 11:14:24 -0700 Subject: Ensure pgalloc.MemoryFile.fileSize is always chunk-aligned. findAvailableLocked() may return a non-aligned FileRange.End after expansion since it may round FileRange.Start down to a hugepage boundary. PiperOrigin-RevId: 315520321 --- pkg/sentry/pgalloc/pgalloc.go | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) (limited to 'pkg') diff --git a/pkg/sentry/pgalloc/pgalloc.go b/pkg/sentry/pgalloc/pgalloc.go index c8d9facc2..46f19d218 100644 --- a/pkg/sentry/pgalloc/pgalloc.go +++ b/pkg/sentry/pgalloc/pgalloc.go @@ -393,16 +393,17 @@ func (f *MemoryFile) Allocate(length uint64, kind usage.MemoryKind) (platform.Fi return platform.FileRange{}, syserror.ENOMEM } - // Expand the file if needed. Note that findAvailableRange will - // appropriately double the fileSize when required. + // Expand the file if needed. if int64(fr.End) > f.fileSize { - if err := f.file.Truncate(int64(fr.End)); err != nil { + // Round the new file size up to be chunk-aligned. + newFileSize := (int64(fr.End) + chunkMask) &^ chunkMask + if err := f.file.Truncate(newFileSize); err != nil { return platform.FileRange{}, err } - f.fileSize = int64(fr.End) + f.fileSize = newFileSize f.mappingsMu.Lock() oldMappings := f.mappings.Load().([]uintptr) - newMappings := make([]uintptr, f.fileSize>>chunkShift) + newMappings := make([]uintptr, newFileSize>>chunkShift) copy(newMappings, oldMappings) f.mappings.Store(newMappings) f.mappingsMu.Unlock() -- cgit v1.2.3