From ae136df84998ea98f184f9136c71784d37cf4d09 Mon Sep 17 00:00:00 2001
From: Ayush Ranjan <ayushranjan@google.com>
Date: Thu, 10 Nov 2022 10:59:50 -0800
Subject: [PATCH] Add nil-check for parent mount in umount(2) while handling
 mount propagation.

PiperOrigin-RevId: 487585583
---
 pkg/sentry/vfs/mount.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pkg/sentry/vfs/mount.go b/pkg/sentry/vfs/mount.go
index c6e0fe612..2886ff7c2 100644
--- a/pkg/sentry/vfs/mount.go
+++ b/pkg/sentry/vfs/mount.go
@@ -654,7 +654,7 @@ func (vfs *VirtualFilesystem) UmountAt(ctx context.Context, creds *auth.Credenti
 
 	umountTree := []*Mount{vd.mount}
 	parent, mountpoint := vd.mount.parent(), vd.mount.point()
-	if parent.propType == Shared {
+	if parent != nil && parent.propType == Shared {
 		for peer := parent.sharedList.Front(); peer != nil; peer = peer.sharedEntry.Next() {
 			if peer == parent {
 				continue