From b466ede1eab7c803674d8375e193b87a0e6f936b Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Sun, 7 Feb 2021 18:13:51 +0100
Subject: Kernel: Make sure we can allocate kernel stack before creating thread

Wrap thread creation in a Thread::try_create() helper that first
allocates a kernel stack region. If that allocation fails, we propagate
an ENOMEM error to the caller.

This avoids the situation where a thread is half-constructed, without a
valid kernel stack, and avoids having to do messy cleanup in that case.
---
 Kernel/Syscalls/thread.cpp | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

(limited to 'Kernel/Syscalls/thread.cpp')

diff --git a/Kernel/Syscalls/thread.cpp b/Kernel/Syscalls/thread.cpp
index 5f975c8ffd..d65591833a 100644
--- a/Kernel/Syscalls/thread.cpp
+++ b/Kernel/Syscalls/thread.cpp
@@ -60,11 +60,11 @@ int Process::sys$create_thread(void* (*entry)(void*), Userspace<const Syscall::S
 
     // FIXME: Do something with guard pages?
 
-    auto thread = adopt(*new Thread(*this));
-    if (!thread->was_created()) {
-        // Could not fully create a thread
-        return -ENOMEM;
-    }
+    auto thread_or_error = Thread::try_create(*this);
+    if (thread_or_error.is_error())
+        return thread_or_error.error();
+
+    auto& thread = thread_or_error.value();
 
     // We know this thread is not the main_thread,
     // So give it a unique name until the user calls $set_thread_name on it
-- 
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