From 583bd20f02fabb2b41f42d2ae8feb1994c0e4fb4 Mon Sep 17 00:00:00 2001
From: Subv <subv2112@gmail.com>
Date: Fri, 30 Nov 2018 16:06:49 -0500
Subject: [PATCH] Services/VI: Dereferencing an uninitialized std::optional is
 undefined behavior.

Assert that it is not empty before using it in the DequeueBuffer wait callback.
---
 src/core/hle/service/vi/vi.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/core/hle/service/vi/vi.cpp b/src/core/hle/service/vi/vi.cpp
index 5120abfffe..412d5b0c98 100644
--- a/src/core/hle/service/vi/vi.cpp
+++ b/src/core/hle/service/vi/vi.cpp
@@ -542,6 +542,8 @@ private:
                         // Repeat TransactParcel DequeueBuffer when a buffer is available
                         auto buffer_queue = nv_flinger->GetBufferQueue(id);
                         std::optional<u32> slot = buffer_queue->DequeueBuffer(width, height);
+                        ASSERT_MSG(slot != std::nullopt, "Could not dequeue buffer.");
+
                         IGBPDequeueBufferResponseParcel response{*slot};
                         ctx.WriteBuffer(response.Serialize());
                         IPC::ResponseBuilder rb{ctx, 2};