fix invalid file read (#6024)

weed/filer/filechunk_group.go

@@ -1,6 +1,7 @@
 package filer
 
 import (
+	"io"
 	"sync"
 
 	"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
@@ -44,6 +45,9 @@ func (group *ChunkGroup) AddChunk(chunk *filer_pb.FileChunk) error {
 }
 
 func (group *ChunkGroup) ReadDataAt(fileSize int64, buff []byte, offset int64) (n int, tsNs int64, err error) {
+	if offset >= fileSize {
+		return 0, 0, io.EOF
+	}
 
 	group.sectionsLock.RLock()
 	defer group.sectionsLock.RUnlock()

weed/mount/filehandle_read.go

@@ -47,6 +47,9 @@ func (fh *FileHandle) readFromChunks(buff []byte, offset int64) (int64, int64, e
 	if fileSize == 0 {
 		glog.V(1).Infof("empty fh %v", fileFullPath)
 		return 0, 0, io.EOF
+	} else if offset >= fileSize {
+		glog.V(1).Infof("invalid read, fileSize %d, offset %d for %s", fileSize, offset, fileFullPath)
+		return 0, 0, io.EOF
 	}
 
 	if offset < int64(len(entry.Content)) {
@@ -66,7 +69,7 @@ func (fh *FileHandle) readFromChunks(buff []byte, offset int64) (int64, int64, e
 	return int64(totalRead), ts, err
 }
 
-func (fh *FileHandle) downloadRemoteEntry(entry *LockedEntry) (error) {
+func (fh *FileHandle) downloadRemoteEntry(entry *LockedEntry) error {
 
 	fileFullPath := fh.FullPath()
 	dir, _ := fileFullPath.DirAndName()