From dc798302e7d4e55f518e10fa00d654abd6695e5c Mon Sep 17 00:00:00 2001
From: Jan Beulich <jbeulich@suse.com>
Date: Tue, 7 Jun 2022 14:18:41 +0200
Subject: [PATCH] IOMMU: make domctl handler tolerate NULL domain

Besides the reporter's issue of hitting a NULL deref when !CONFIG_GDBSX,
XEN_DOMCTL_test_assign_device can legitimately end up having NULL passed
here, when the domctl was passed DOMID_INVALID.

Fixes: 71e617a6b8f6 ("use is_iommu_enabled() where appropriate...")
Reported-by: Cheyenne Wills <cheyenne.wills@gmail.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
master commit: fa4d84e6dd3c3bfd23a525b75a5483d4ce15adbb
master date: 2022-04-26 10:25:54 +0200
---
 xen/drivers/passthrough/iommu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
index 98c6550a36..9a2b1e7808 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -515,7 +515,7 @@ int iommu_do_domctl(
 {
     int ret = -ENODEV;
 
-    if ( !is_iommu_enabled(d) )
+    if ( !(d ? is_iommu_enabled(d) : iommu_enabled) )
         return -EOPNOTSUPP;
 
 #ifdef CONFIG_HAS_PCI