Merge release-20200323.0-69-gfc99a7e (automated)

9 files changed, 96 insertions, 30 deletions

diff --git a/pkg/sentry/kernel/epoll/epoll_list.go b/pkg/sentry/kernel/epoll/epoll_list.go
index 37f757fa8..a018f7b5c 100755
--- a/pkg/sentry/kernel/epoll/epoll_list.go
+++ b/pkg/sentry/kernel/epoll/epoll_list.go
@@ -52,12 +52,21 @@ func (l *pollEntryList) Back() *pollEntry {
 	return l.tail
 }
 
+// Len returns the number of elements in the list.
+//
+// NOTE: This is an O(n) operation.
+func (l *pollEntryList) Len() (count int) {
+	for e := l.Front(); e != nil; e = e.Next() {
+		count++
+	}
+	return count
+}
+
 // PushFront inserts the element e at the front of list l.
 func (l *pollEntryList) PushFront(e *pollEntry) {
 	linker := pollEntryElementMapper{}.linkerFor(e)
 	linker.SetNext(l.head)
 	linker.SetPrev(nil)
-
 	if l.head != nil {
 		pollEntryElementMapper{}.linkerFor(l.head).SetPrev(e)
 	} else {
@@ -72,7 +81,6 @@ func (l *pollEntryList) PushBack(e *pollEntry) {
 	linker := pollEntryElementMapper{}.linkerFor(e)
 	linker.SetNext(nil)
 	linker.SetPrev(l.tail)
-
 	if l.tail != nil {
 		pollEntryElementMapper{}.linkerFor(l.tail).SetNext(e)
 	} else {
@@ -93,7 +101,6 @@ func (l *pollEntryList) PushBackList(m *pollEntryList) {
 
 		l.tail = m.tail
 	}
-
 	m.head = nil
 	m.tail = nil
 }
diff --git a/pkg/sentry/kernel/futex/waiter_list.go b/pkg/sentry/kernel/futex/waiter_list.go
index 204eededf..1b7a92b62 100755
--- a/pkg/sentry/kernel/futex/waiter_list.go
+++ b/pkg/sentry/kernel/futex/waiter_list.go
@@ -52,12 +52,21 @@ func (l *waiterList) Back() *Waiter {
 	return l.tail
 }
 
+// Len returns the number of elements in the list.
+//
+// NOTE: This is an O(n) operation.
+func (l *waiterList) Len() (count int) {
+	for e := l.Front(); e != nil; e = e.Next() {
+		count++
+	}
+	return count
+}
+
 // PushFront inserts the element e at the front of list l.
 func (l *waiterList) PushFront(e *Waiter) {
 	linker := waiterElementMapper{}.linkerFor(e)
 	linker.SetNext(l.head)
 	linker.SetPrev(nil)
-
 	if l.head != nil {
 		waiterElementMapper{}.linkerFor(l.head).SetPrev(e)
 	} else {
@@ -72,7 +81,6 @@ func (l *waiterList) PushBack(e *Waiter) {
 	linker := waiterElementMapper{}.linkerFor(e)
 	linker.SetNext(nil)
 	linker.SetPrev(l.tail)
-
 	if l.tail != nil {
 		waiterElementMapper{}.linkerFor(l.tail).SetNext(e)
 	} else {
@@ -93,7 +101,6 @@ func (l *waiterList) PushBackList(m *waiterList) {
 
 		l.tail = m.tail
 	}
-
 	m.head = nil
 	m.tail = nil
 }
diff --git a/pkg/sentry/kernel/kernel.go b/pkg/sentry/kernel/kernel.go
index 0a448b57c..2e6f42b92 100644
--- a/pkg/sentry/kernel/kernel.go
+++ b/pkg/sentry/kernel/kernel.go
@@ -564,15 +564,25 @@ func (ts *TaskSet) unregisterEpollWaiters() {
 
 	ts.mu.RLock()
 	defer ts.mu.RUnlock()
+
+	// Tasks that belong to the same process could potentially point to the
+	// same FDTable. So we retain a map of processed ones to avoid
+	// processing the same FDTable multiple times.
+	processed := make(map[*FDTable]struct{})
 	for t := range ts.Root.tids {
 		// We can skip locking Task.mu here since the kernel is paused.
-		if t.fdTable != nil {
-			t.fdTable.forEach(func(_ int32, file *fs.File, _ *vfs.FileDescription, _ FDFlags) {
-				if e, ok := file.FileOperations.(*epoll.EventPoll); ok {
-					e.UnregisterEpollWaiters()
-				}
-			})
+		if t.fdTable == nil {
+			continue
+		}
+		if _, ok := processed[t.fdTable]; ok {
+			continue
 		}
+		t.fdTable.forEach(func(_ int32, file *fs.File, _ *vfs.FileDescription, _ FDFlags) {
+			if e, ok := file.FileOperations.(*epoll.EventPoll); ok {
+				e.UnregisterEpollWaiters()
+			}
+		})
+		processed[t.fdTable] = struct{}{}
 	}
 }
 
diff --git a/pkg/sentry/kernel/pending_signals_list.go b/pkg/sentry/kernel/pending_signals_list.go
index 8eb40ac2c..2685c631a 100755
--- a/pkg/sentry/kernel/pending_signals_list.go
+++ b/pkg/sentry/kernel/pending_signals_list.go
@@ -52,12 +52,21 @@ func (l *pendingSignalList) Back() *pendingSignal {
 	return l.tail
 }
 
+// Len returns the number of elements in the list.
+//
+// NOTE: This is an O(n) operation.
+func (l *pendingSignalList) Len() (count int) {
+	for e := l.Front(); e != nil; e = e.Next() {
+		count++
+	}
+	return count
+}
+
 // PushFront inserts the element e at the front of list l.
 func (l *pendingSignalList) PushFront(e *pendingSignal) {
 	linker := pendingSignalElementMapper{}.linkerFor(e)
 	linker.SetNext(l.head)
 	linker.SetPrev(nil)
-
 	if l.head != nil {
 		pendingSignalElementMapper{}.linkerFor(l.head).SetPrev(e)
 	} else {
@@ -72,7 +81,6 @@ func (l *pendingSignalList) PushBack(e *pendingSignal) {
 	linker := pendingSignalElementMapper{}.linkerFor(e)
 	linker.SetNext(nil)
 	linker.SetPrev(l.tail)
-
 	if l.tail != nil {
 		pendingSignalElementMapper{}.linkerFor(l.tail).SetNext(e)
 	} else {
@@ -93,7 +101,6 @@ func (l *pendingSignalList) PushBackList(m *pendingSignalList) {
 
 		l.tail = m.tail
 	}
-
 	m.head = nil
 	m.tail = nil
 }
diff --git a/pkg/sentry/kernel/process_group_list.go b/pkg/sentry/kernel/process_group_list.go
index 40c1a13a4..3c5ea8aa7 100755
--- a/pkg/sentry/kernel/process_group_list.go
+++ b/pkg/sentry/kernel/process_group_list.go
@@ -52,12 +52,21 @@ func (l *processGroupList) Back() *ProcessGroup {
 	return l.tail
 }
 
+// Len returns the number of elements in the list.
+//
+// NOTE: This is an O(n) operation.
+func (l *processGroupList) Len() (count int) {
+	for e := l.Front(); e != nil; e = e.Next() {
+		count++
+	}
+	return count
+}
+
 // PushFront inserts the element e at the front of list l.
 func (l *processGroupList) PushFront(e *ProcessGroup) {
 	linker := processGroupElementMapper{}.linkerFor(e)
 	linker.SetNext(l.head)
 	linker.SetPrev(nil)
-
 	if l.head != nil {
 		processGroupElementMapper{}.linkerFor(l.head).SetPrev(e)
 	} else {
@@ -72,7 +81,6 @@ func (l *processGroupList) PushBack(e *ProcessGroup) {
 	linker := processGroupElementMapper{}.linkerFor(e)
 	linker.SetNext(nil)
 	linker.SetPrev(l.tail)
-
 	if l.tail != nil {
 		processGroupElementMapper{}.linkerFor(l.tail).SetNext(e)
 	} else {
@@ -93,7 +101,6 @@ func (l *processGroupList) PushBackList(m *processGroupList) {
 
 		l.tail = m.tail
 	}
-
 	m.head = nil
 	m.tail = nil
 }
diff --git a/pkg/sentry/kernel/semaphore/waiter_list.go b/pkg/sentry/kernel/semaphore/waiter_list.go
index 27120afe3..4bfe5ff95 100755
--- a/pkg/sentry/kernel/semaphore/waiter_list.go
+++ b/pkg/sentry/kernel/semaphore/waiter_list.go
@@ -52,12 +52,21 @@ func (l *waiterList) Back() *waiter {
 	return l.tail
 }
 
+// Len returns the number of elements in the list.
+//
+// NOTE: This is an O(n) operation.
+func (l *waiterList) Len() (count int) {
+	for e := l.Front(); e != nil; e = e.Next() {
+		count++
+	}
+	return count
+}
+
 // PushFront inserts the element e at the front of list l.
 func (l *waiterList) PushFront(e *waiter) {
 	linker := waiterElementMapper{}.linkerFor(e)
 	linker.SetNext(l.head)
 	linker.SetPrev(nil)
-
 	if l.head != nil {
 		waiterElementMapper{}.linkerFor(l.head).SetPrev(e)
 	} else {
@@ -72,7 +81,6 @@ func (l *waiterList) PushBack(e *waiter) {
 	linker := waiterElementMapper{}.linkerFor(e)
 	linker.SetNext(nil)
 	linker.SetPrev(l.tail)
-
 	if l.tail != nil {
 		waiterElementMapper{}.linkerFor(l.tail).SetNext(e)
 	} else {
@@ -93,7 +101,6 @@ func (l *waiterList) PushBackList(m *waiterList) {
 
 		l.tail = m.tail
 	}
-
 	m.head = nil
 	m.tail = nil
 }
diff --git a/pkg/sentry/kernel/session_list.go b/pkg/sentry/kernel/session_list.go
index 8174f413d..768482ab6 100755
--- a/pkg/sentry/kernel/session_list.go
+++ b/pkg/sentry/kernel/session_list.go
@@ -52,12 +52,21 @@ func (l *sessionList) Back() *Session {
 	return l.tail
 }
 
+// Len returns the number of elements in the list.
+//
+// NOTE: This is an O(n) operation.
+func (l *sessionList) Len() (count int) {
+	for e := l.Front(); e != nil; e = e.Next() {
+		count++
+	}
+	return count
+}
+
 // PushFront inserts the element e at the front of list l.
 func (l *sessionList) PushFront(e *Session) {
 	linker := sessionElementMapper{}.linkerFor(e)
 	linker.SetNext(l.head)
 	linker.SetPrev(nil)
-
 	if l.head != nil {
 		sessionElementMapper{}.linkerFor(l.head).SetPrev(e)
 	} else {
@@ -72,7 +81,6 @@ func (l *sessionList) PushBack(e *Session) {
 	linker := sessionElementMapper{}.linkerFor(e)
 	linker.SetNext(nil)
 	linker.SetPrev(l.tail)
-
 	if l.tail != nil {
 		sessionElementMapper{}.linkerFor(l.tail).SetNext(e)
 	} else {
@@ -93,7 +101,6 @@ func (l *sessionList) PushBackList(m *sessionList) {
 
 		l.tail = m.tail
 	}
-
 	m.head = nil
 	m.tail = nil
 }
diff --git a/pkg/sentry/kernel/socket_list.go b/pkg/sentry/kernel/socket_list.go
index ac93e2365..294aa99fe 100755
--- a/pkg/sentry/kernel/socket_list.go
+++ b/pkg/sentry/kernel/socket_list.go
@@ -52,12 +52,21 @@ func (l *socketList) Back() *SocketEntry {
 	return l.tail
 }
 
+// Len returns the number of elements in the list.
+//
+// NOTE: This is an O(n) operation.
+func (l *socketList) Len() (count int) {
+	for e := l.Front(); e != nil; e = e.Next() {
+		count++
+	}
+	return count
+}
+
 // PushFront inserts the element e at the front of list l.
 func (l *socketList) PushFront(e *SocketEntry) {
 	linker := socketElementMapper{}.linkerFor(e)
 	linker.SetNext(l.head)
 	linker.SetPrev(nil)
-
 	if l.head != nil {
 		socketElementMapper{}.linkerFor(l.head).SetPrev(e)
 	} else {
@@ -72,7 +81,6 @@ func (l *socketList) PushBack(e *SocketEntry) {
 	linker := socketElementMapper{}.linkerFor(e)
 	linker.SetNext(nil)
 	linker.SetPrev(l.tail)
-
 	if l.tail != nil {
 		socketElementMapper{}.linkerFor(l.tail).SetNext(e)
 	} else {
@@ -93,7 +101,6 @@ func (l *socketList) PushBackList(m *socketList) {
 
 		l.tail = m.tail
 	}
-
 	m.head = nil
 	m.tail = nil
 }
diff --git a/pkg/sentry/kernel/task_list.go b/pkg/sentry/kernel/task_list.go
index 4dfcdbf2c..e7a3a3d20 100755
--- a/pkg/sentry/kernel/task_list.go
+++ b/pkg/sentry/kernel/task_list.go
@@ -52,12 +52,21 @@ func (l *taskList) Back() *Task {
 	return l.tail
 }
 
+// Len returns the number of elements in the list.
+//
+// NOTE: This is an O(n) operation.
+func (l *taskList) Len() (count int) {
+	for e := l.Front(); e != nil; e = e.Next() {
+		count++
+	}
+	return count
+}
+
 // PushFront inserts the element e at the front of list l.
 func (l *taskList) PushFront(e *Task) {
 	linker := taskElementMapper{}.linkerFor(e)
 	linker.SetNext(l.head)
 	linker.SetPrev(nil)
-
 	if l.head != nil {
 		taskElementMapper{}.linkerFor(l.head).SetPrev(e)
 	} else {
@@ -72,7 +81,6 @@ func (l *taskList) PushBack(e *Task) {
 	linker := taskElementMapper{}.linkerFor(e)
 	linker.SetNext(nil)
 	linker.SetPrev(l.tail)
-
 	if l.tail != nil {
 		taskElementMapper{}.linkerFor(l.tail).SetNext(e)
 	} else {
@@ -93,7 +101,6 @@ func (l *taskList) PushBackList(m *taskList) {
 
 		l.tail = m.tail
 	}
-
 	m.head = nil
 	m.tail = nil
 }