From: Jan Beulich <jbeulich@suse.com>
Date: Wed, 22 Apr 2020 11:01:10 +0000 (+0200)
Subject: x86: validate VM assist value in arch_set_info_guest()
X-Git-Tag: archive/raspbian/4.14.0+80-gd101b417b7-1+rpi1^2~63^2~373
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=a62c6fe05c4ae905b7d4cb0ca946508b7f96d522;p=xen.git

x86: validate VM assist value in arch_set_info_guest()

While I can't spot anything that would go wrong, just like the
respective hypercall only permits applicable bits to be set, we should
also do so when loading guest context.

Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
---

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 7f18f4a88a..a4428190d5 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -932,6 +932,9 @@ int arch_set_info_guest(
         }
     }
 
+    if ( v->vcpu_id == 0 && (c(vm_assist) & ~arch_vm_assist_valid_mask(d)) )
+        return -EINVAL;
+
     if ( is_hvm_domain(d) )
     {
         for ( i = 0; i < ARRAY_SIZE(v->arch.dr); ++i )