From 1bd17464473a2ea7dd1e1c5abef50fa3f30a56b5 Mon Sep 17 00:00:00 2001
From: Suren Baghdasaryan <surenb@google.com>
Date: Thu, 31 Mar 2022 21:18:20 -0700
Subject: [PATCH] init: Treat failure to create a process group as fatal

During process startup, system creates a process group and places the
new process in it. If process group creation fails for some reason, the
new child process will stay in its parent's group. This poses danger
when the child is being frozen because the whole group is affected and
its parent is being frozen as well.
Fix this by treating group creation failure as a fatal error which would
prevent the app from starting.

Bug: 227395690
Test: fake group creation failure and confirm service failure to start
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: I83261bef803751759c7fd709bf1ccd33ccad3a0b
---
 init/service.cpp | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/init/service.cpp b/init/service.cpp
index 2ebf87eb1..077477a15 100644
--- a/init/service.cpp
+++ b/init/service.cpp
@@ -491,10 +491,15 @@ void Service::RunService(const std::optional<MountNamespace>& override_mount_nam
 
     // Wait until the cgroups have been created and until the cgroup controllers have been
     // activated.
-    if (std::byte byte; read((*pipefd)[0], &byte, 1) < 0) {
+    char byte = 0;
+    if (read((*pipefd)[0], &byte, 1) < 0) {
         PLOG(ERROR) << "failed to read from notification channel";
     }
     pipefd.reset();
+    if (!byte) {
+        LOG(FATAL) << "Service '" << name_  << "' failed to start due to a fatal error";
+        _exit(EXIT_FAILURE);
+    }
 
     if (task_profiles_.size() > 0 && !SetTaskProfiles(getpid(), task_profiles_)) {
         LOG(ERROR) << "failed to set task profiles";
@@ -647,9 +652,14 @@ Result<void> Service::Start() {
                       limit_percent_ != -1 || !limit_property_.empty();
     errno = -createProcessGroup(proc_attr_.uid, pid_, use_memcg);
     if (errno != 0) {
-        PLOG(ERROR) << "createProcessGroup(" << proc_attr_.uid << ", " << pid_
-                    << ") failed for service '" << name_ << "'";
-    } else if (use_memcg) {
+        if (char byte = 0; write((*pipefd)[1], &byte, 1) < 0) {
+            return ErrnoError() << "sending notification failed";
+        }
+        return Error() << "createProcessGroup(" << proc_attr_.uid << ", " << pid_
+                       << ") failed for service '" << name_ << "'";
+    }
+
+    if (use_memcg) {
         ConfigureMemcg();
     }
 
@@ -657,7 +667,7 @@ Result<void> Service::Start() {
         LmkdRegister(name_, proc_attr_.uid, pid_, oom_score_adjust_);
     }
 
-    if (write((*pipefd)[1], "", 1) < 0) {
+    if (char byte = 1; write((*pipefd)[1], &byte, 1) < 0) {
         return ErrnoError() << "sending notification failed";
     }