From a27f0debca4c0fe8cd916d2406124f9d30ae5dbe Mon Sep 17 00:00:00 2001
From: Joachim Henze <Joachim.Henze@reactos.org>
Date: Tue, 15 Sep 2020 20:54:50 +0200
Subject: [PATCH] [MMIXER] Fix NULL dereference CORE-17276

This lead to a crash of winmm:mixer
during "GCCLin_x86 on Test VBox".

The crash was exposed when new code paths
were activated by 0.4.15-dev-791-g
6d7ebc20481a587bd19e8a8049317113071b0817

I do intend to port this commit back into 0.4.14RC.
---
 sdk/lib/drivers/sound/mmixer/sup.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sdk/lib/drivers/sound/mmixer/sup.c b/sdk/lib/drivers/sound/mmixer/sup.c
index 06f342b12e8..4fa8c080309 100644
--- a/sdk/lib/drivers/sound/mmixer/sup.c
+++ b/sdk/lib/drivers/sound/mmixer/sup.c
@@ -690,6 +690,8 @@ MMixerSetGetVolumeControlDetails(
 
     /* get input */
     Input = (LPMIXERCONTROLDETAILS_UNSIGNED)MixerControlDetails->paDetails;
+    if (!Input)
+        return MM_STATUS_UNSUCCESSFUL; /* to prevent dereferencing NULL */
 
     if (bSet)
     {