4 files changed, 9 insertions, 1 deletions
diff --git a/pkg/sentry/fs/inode.go b/pkg/sentry/fs/inode.go
index f4ddfa406..2d43dff1d 100644
--- a/pkg/sentry/fs/inode.go
+++ b/pkg/sentry/fs/inode.go
@@ -344,6 +344,10 @@ func (i *Inode) SetTimestamps(ctx context.Context, d *Dirent, ts TimeSpec) error
 
 // Truncate calls i.InodeOperations.Truncate with i as the Inode.
 func (i *Inode) Truncate(ctx context.Context, d *Dirent, size int64) error {
+	if IsDir(i.StableAttr) {
+		return syserror.EISDIR
+	}
+
 	if i.overlay != nil {
 		return overlayTruncate(ctx, i.overlay, d, size)
 	}
diff --git a/pkg/sentry/fs/inode_overlay.go b/pkg/sentry/fs/inode_overlay.go
index 5a388dad1..a09147080 100644
--- a/pkg/sentry/fs/inode_overlay.go
+++ b/pkg/sentry/fs/inode_overlay.go
@@ -462,7 +462,9 @@ func overlayBind(ctx context.Context, o *overlayEntry, parent *Dirent, name stri
 		inode.DecRef()
 		return nil, err
 	}
-	return NewDirent(ctx, newOverlayInode(ctx, entry, inode.MountSource), name), nil
+	// Use the parent's MountSource, since that corresponds to the overlay,
+	// and not the upper filesystem.
+	return NewDirent(ctx, newOverlayInode(ctx, entry, parent.Inode.MountSource), name), nil
 }
 
 func overlayBoundEndpoint(o *overlayEntry, path string) transport.BoundEndpoint {
diff --git a/pkg/sentry/fs/tty/master.go b/pkg/sentry/fs/tty/master.go
index 19b7557d5..bc56be696 100644
--- a/pkg/sentry/fs/tty/master.go
+++ b/pkg/sentry/fs/tty/master.go
@@ -32,6 +32,7 @@ import (
 // +stateify savable
 type masterInodeOperations struct {
 	fsutil.SimpleFileInode
+	fsutil.InodeNoopTruncate
 
 	// d is the containing dir.
 	d *dirInodeOperations
diff --git a/pkg/sentry/fs/tty/slave.go b/pkg/sentry/fs/tty/slave.go
index 944c4ada1..4cbea0367 100644
--- a/pkg/sentry/fs/tty/slave.go
+++ b/pkg/sentry/fs/tty/slave.go
@@ -31,6 +31,7 @@ import (
 // +stateify savable
 type slaveInodeOperations struct {
 	fsutil.SimpleFileInode
+	fsutil.InodeNoopTruncate
 
 	// d is the containing dir.
 	d *dirInodeOperations