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.

1 files changed, 5 insertions, 5 deletions

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