vm/gce: fix image archive creation

See the added comment.

1 files changed, 8 insertions, 4 deletions

diff --git a/vm/gce/gce.go b/vm/gce/gce.go
index 0ba38298e..81cd02f67 100644
--- a/vm/gce/gce.go
+++ b/vm/gce/gce.go
@@ -346,10 +346,14 @@ func uploadImageToGCS(localImage, gcsImage string) error {
 		Mode:     0640,
 		Size:     localStat.Size(),
 		ModTime:  time.Now(),
-		Uid:      0,
-		Uname:    "root",
-		Gid:      0,
-		Gname:    "",
+		// This is hacky but we actually need these large uids.
+		// GCE understands only the old GNU tar format and
+		// there is no direct way to force tar package to use GNU format.
+		// But these large numbers force tar to switch to GNU format.
+		Uid:   100000000,
+		Gid:   100000000,
+		Uname: "syzkaller",
+		Gname: "syzkaller",
 	}
 	if err := tarWriter.WriteHeader(tarHeader); err != nil {
 		return fmt.Errorf("failed to write image tar header: %v", err)