From 0f45bbbc404e2d1257476f9caa6644c209ec2c90 Mon Sep 17 00:00:00 2001
From: Roger Pau Monne <roger.pau@citrix.com>
Date: Thu, 31 Oct 2019 12:58:29 +0100
Subject: [PATCH] x86/shim: copy back the result of EVTCHNOP_status
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The event channel data was not copied back to guest memory, fix this
by doing the copy.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Wei Liu <wl@xen.org>
Release-acked-by: Juergen Gross <jgross@suse.com>
---
 xen/arch/x86/pv/shim.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/xen/arch/x86/pv/shim.c b/xen/arch/x86/pv/shim.c
index 4329eaaefe..35bf3945ac 100644
--- a/xen/arch/x86/pv/shim.c
+++ b/xen/arch/x86/pv/shim.c
@@ -514,6 +514,9 @@ static long pv_shim_event_channel_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
         else
             rc = xen_hypercall_event_channel_op(EVTCHNOP_status, &status);
 
+        if ( !rc && __copy_to_guest(arg, &status, 1) )
+            rc = -EFAULT;
+
         break;
     }
 
-- 
2.39.5