From bb91bed576f244bb1ddf2faee64c36b18f644901 Mon Sep 17 00:00:00 2001
From: Brian Gianforcaro <bgianf@serenityos.org>
Date: Tue, 18 May 2021 02:07:25 -0700
Subject: [PATCH] Kernel: Make ProcessGroup::find_or_create API OOM safe

Make ProcessGroup::find_or_create & ProcessGroup::create OOM safe, by
moving to adopt_ref_if_nonnull.
---
 Kernel/ProcessGroup.cpp     | 8 ++++----
 Kernel/ProcessGroup.h       | 4 ++--
 Kernel/Syscalls/setpgid.cpp | 3 +++
 3 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/Kernel/ProcessGroup.cpp b/Kernel/ProcessGroup.cpp
index 938b41152f..3a92151e51 100644
--- a/Kernel/ProcessGroup.cpp
+++ b/Kernel/ProcessGroup.cpp
@@ -17,10 +17,10 @@ ProcessGroup::~ProcessGroup()
     g_process_groups->remove(this);
 }
 
-NonnullRefPtr<ProcessGroup> ProcessGroup::create(ProcessGroupID pgid)
+RefPtr<ProcessGroup> ProcessGroup::create(ProcessGroupID pgid)
 {
-    auto process_group = adopt_ref(*new ProcessGroup(pgid));
-    {
+    auto process_group = adopt_ref_if_nonnull(new ProcessGroup(pgid));
+    if (process_group) {
         ScopedSpinLock lock(g_process_groups_lock);
         g_process_groups->prepend(process_group);
     }
@@ -28,7 +28,7 @@ NonnullRefPtr<ProcessGroup> ProcessGroup::create(ProcessGroupID pgid)
     return process_group;
 }
 
-NonnullRefPtr<ProcessGroup> ProcessGroup::find_or_create(ProcessGroupID pgid)
+RefPtr<ProcessGroup> ProcessGroup::find_or_create(ProcessGroupID pgid)
 {
     ScopedSpinLock lock(g_process_groups_lock);
 
diff --git a/Kernel/ProcessGroup.h b/Kernel/ProcessGroup.h
index 45fb4b38fa..8ae5f295f5 100644
--- a/Kernel/ProcessGroup.h
+++ b/Kernel/ProcessGroup.h
@@ -28,8 +28,8 @@ class ProcessGroup
 public:
     ~ProcessGroup();
 
-    static NonnullRefPtr<ProcessGroup> create(ProcessGroupID);
-    static NonnullRefPtr<ProcessGroup> find_or_create(ProcessGroupID);
+    static RefPtr<ProcessGroup> create(ProcessGroupID);
+    static RefPtr<ProcessGroup> find_or_create(ProcessGroupID);
     static RefPtr<ProcessGroup> from_pgid(ProcessGroupID);
 
     const ProcessGroupID& pgid() const { return m_pgid; }
diff --git a/Kernel/Syscalls/setpgid.cpp b/Kernel/Syscalls/setpgid.cpp
index 3398bcca70..e81baf3051 100644
--- a/Kernel/Syscalls/setpgid.cpp
+++ b/Kernel/Syscalls/setpgid.cpp
@@ -116,6 +116,9 @@ KResultOr<int> Process::sys$setpgid(pid_t specified_pid, pid_t specified_pgid)
     }
     // FIXME: There are more EPERM conditions to check for here..
     process->m_pg = ProcessGroup::find_or_create(new_pgid);
+    if (!process->m_pg) {
+        return ENOMEM;
+    }
     return 0;
 }