Merge release-20190806.1-309-gfbe6b50 (automated)

pkg/sentry/kernel/fd_table.go

@@ -81,6 +81,9 @@ type FDTable struct {
 	// mu protects below.
 	mu sync.Mutex `state:"nosave"`
 
+	// next is start position to find fd.
+	next int32
+
 	// used contains the number of non-nil entries. It must be accessed
 	// atomically. It may be read atomically without holding mu (but not
 	// written).
@@ -226,6 +229,11 @@ func (f *FDTable) NewFDs(ctx context.Context, fd int32, files []*fs.File, flags
 	f.mu.Lock()
 	defer f.mu.Unlock()
 
+	// From f.next to find available fd.
+	if fd < f.next {
+		fd = f.next
+	}
+
 	// Install all entries.
 	for i := fd; i < end && len(fds) < len(files); i++ {
 		if d, _, _ := f.get(i); d == nil {
@@ -242,6 +250,11 @@ func (f *FDTable) NewFDs(ctx context.Context, fd int32, files []*fs.File, flags
 		return nil, syscall.EMFILE
 	}
 
+	if fd == f.next {
+		// Update next search start position.
+		f.next = fds[len(fds)-1] + 1
+	}
+
 	return fds, nil
 }
 
@@ -361,6 +374,11 @@ func (f *FDTable) Remove(fd int32) *fs.File {
 	f.mu.Lock()
 	defer f.mu.Unlock()
 
+	// Update current available position.
+	if fd < f.next {
+		f.next = fd
+	}
+
 	orig, _, _ := f.get(fd)
 	if orig != nil {
 		orig.IncRef()             // Reference for caller.
@@ -377,6 +395,10 @@ func (f *FDTable) RemoveIf(cond func(*fs.File, FDFlags) bool) {
 	f.forEach(func(fd int32, file *fs.File, flags FDFlags) {
 		if cond(file, flags) {
 			f.set(fd, nil, FDFlags{}) // Clear from table.
+			// Update current available position.
+			if fd < f.next {
+				f.next = fd
+			}
 		}
 	})
 }

pkg/sentry/kernel/kernel_state_autogen.go

@@ -69,6 +69,7 @@ func (x *FDTable) save(m state.Map) {
 	m.Save("AtomicRefCount", &x.AtomicRefCount)
 	m.Save("k", &x.k)
 	m.Save("uid", &x.uid)
+	m.Save("next", &x.next)
 	m.Save("used", &x.used)
 }
 
@@ -77,6 +78,7 @@ func (x *FDTable) load(m state.Map) {
 	m.Load("AtomicRefCount", &x.AtomicRefCount)
 	m.Load("k", &x.k)
 	m.Load("uid", &x.uid)
+	m.Load("next", &x.next)
 	m.Load("used", &x.used)
 	m.LoadValue("descriptorTable", new(map[int32]descriptor), func(y interface{}) { x.loadDescriptorTable(y.(map[int32]descriptor)) })
 }