From f957fb23cf68e72084c7b50569242a07997f96bc Mon Sep 17 00:00:00 2001 From: "chris.zn" Date: Thu, 20 Jun 2019 15:19:05 +0800 Subject: Return ENOENT when reading /proc/{pid}/task of an exited process There will be a deadloop when we use getdents to read /proc/{pid}/task of an exited process Like this: Process A is running Process B: open /proc/{pid of A}/task Process A exits Process B: getdents /proc/{pid of A}/task Then, process B will fall into deadloop, and return "." and ".." in loops and never ends. This patch returns ENOENT when use getdents to read /proc/{pid}/task if the process is just exited. Signed-off-by: chris.zn --- pkg/sentry/fs/proc/task.go | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'pkg/sentry/fs') diff --git a/pkg/sentry/fs/proc/task.go b/pkg/sentry/fs/proc/task.go index b2e36aeee..22554bb88 100644 --- a/pkg/sentry/fs/proc/task.go +++ b/pkg/sentry/fs/proc/task.go @@ -20,6 +20,7 @@ import ( "io" "sort" "strconv" + "syscall" "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/sentry/context" @@ -162,6 +163,11 @@ func (f *subtasksFile) Readdir(ctx context.Context, file *fs.File, ser fs.Dentry // subtask to emit. offset := file.Offset() + tasks := f.t.ThreadGroup().MemberIDs(f.pidns) + if len(tasks) == 0 { + return offset, syscall.ENOENT + } + if offset == 0 { // Serialize "." and "..". root := fs.RootFromContext(ctx) @@ -178,7 +184,6 @@ func (f *subtasksFile) Readdir(ctx context.Context, file *fs.File, ser fs.Dentry } // Serialize tasks. - tasks := f.t.ThreadGroup().MemberIDs(f.pidns) taskInts := make([]int, 0, len(tasks)) for _, tid := range tasks { taskInts = append(taskInts, int(tid)) -- cgit v1.2.3