3 files changed, 37 insertions, 18 deletions
diff --git a/pkg/sentry/fsimpl/proc/subtasks.go b/pkg/sentry/fsimpl/proc/subtasks.go
index f3f4e49b4..611645f3f 100644
--- a/pkg/sentry/fsimpl/proc/subtasks.go
+++ b/pkg/sentry/fsimpl/proc/subtasks.go
@@ -121,8 +121,13 @@ func (i *subtasksInode) Open(rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.O
 }
 
 // Stat implements kernfs.Inode.
-func (i *subtasksInode) Stat(vsfs *vfs.Filesystem) linux.Statx {
-	stat := i.InodeAttrs.Stat(vsfs)
-	stat.Nlink += uint32(i.task.ThreadGroup().Count())
-	return stat
+func (i *subtasksInode) Stat(vsfs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) {
+	stat, err := i.InodeAttrs.Stat(vsfs, opts)
+	if err != nil {
+		return linux.Statx{}, err
+	}
+	if opts.Mask&linux.STATX_NLINK != 0 {
+		stat.Nlink += uint32(i.task.ThreadGroup().Count())
+	}
+	return stat, nil
 }
diff --git a/pkg/sentry/fsimpl/proc/task.go b/pkg/sentry/fsimpl/proc/task.go
index 18e5cd6f6..c0d643f51 100644
--- a/pkg/sentry/fsimpl/proc/task.go
+++ b/pkg/sentry/fsimpl/proc/task.go
@@ -154,12 +154,21 @@ func newTaskOwnedDir(task *kernel.Task, ino uint64, perm linux.FileMode, childre
 }
 
 // Stat implements kernfs.Inode.
-func (i *taskOwnedInode) Stat(fs *vfs.Filesystem) linux.Statx {
-	stat := i.Inode.Stat(fs)
-	uid, gid := i.getOwner(linux.FileMode(stat.Mode))
-	stat.UID = uint32(uid)
-	stat.GID = uint32(gid)
-	return stat
+func (i *taskOwnedInode) Stat(fs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) {
+	stat, err := i.Inode.Stat(fs, opts)
+	if err != nil {
+		return linux.Statx{}, err
+	}
+	if opts.Mask&(linux.STATX_UID|linux.STATX_GID) != 0 {
+		uid, gid := i.getOwner(linux.FileMode(stat.Mode))
+		if opts.Mask&linux.STATX_UID != 0 {
+			stat.UID = uint32(uid)
+		}
+		if opts.Mask&linux.STATX_GID != 0 {
+			stat.GID = uint32(gid)
+		}
+	}
+	return stat, nil
 }
 
 // CheckPermissions implements kernfs.Inode.
@@ -236,7 +245,7 @@ func newNamespaceSymlink(task *kernel.Task, ino uint64, ns string) *kernfs.Dentr
 // member, there is one entry containing three colon-separated fields:
 //   hierarchy-ID:controller-list:cgroup-path"
 func newCgroupData(controllers map[string]string) dynamicInode {
-	buf := bytes.Buffer{}
+	var buf bytes.Buffer
 
 	// The hierarchy ids must be positive integers (for cgroup v1), but the
 	// exact number does not matter, so long as they are unique. We can
diff --git a/pkg/sentry/fsimpl/proc/tasks.go b/pkg/sentry/fsimpl/proc/tasks.go
index 10c08fa90..b1e39c82f 100644
--- a/pkg/sentry/fsimpl/proc/tasks.go
+++ b/pkg/sentry/fsimpl/proc/tasks.go
@@ -211,17 +211,22 @@ func (i *tasksInode) Open(rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.Open
 	return fd.VFSFileDescription(), nil
 }
 
-func (i *tasksInode) Stat(vsfs *vfs.Filesystem) linux.Statx {
-	stat := i.InodeAttrs.Stat(vsfs)
+func (i *tasksInode) Stat(vsfs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) {
+	stat, err := i.InodeAttrs.Stat(vsfs, opts)
+	if err != nil {
+		return linux.Statx{}, err
+	}
 
-	// Add dynamic children to link count.
-	for _, tg := range i.pidns.ThreadGroups() {
-		if leader := tg.Leader(); leader != nil {
-			stat.Nlink++
+	if opts.Mask&linux.STATX_NLINK != 0 {
+		// Add dynamic children to link count.
+		for _, tg := range i.pidns.ThreadGroups() {
+			if leader := tg.Leader(); leader != nil {
+				stat.Nlink++
+			}
 		}
 	}
 
-	return stat
+	return stat, nil
 }
 
 func cpuInfoData(k *kernel.Kernel) string {