[Xen-changelog] [xen stable-4.2] x86/HVM: only allow ring 0 guest code to make hypercalls

[patchbot@xxxxxxx]

commit 420ff58052d22c6f49fb71949a9989256017caae
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Wed Nov 27 09:49:28 2013 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Nov 27 09:49:28 2013 +0100

    x86/HVM: only allow ring 0 guest code to make hypercalls
    
    Anything else would allow for privilege escalation.
    
    This is CVE-2013-4554 / XSA-76.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
    master commit: 5c447caaf49192c7b2c057ffbb565ce72aac666d
    master date: 2013-11-27 09:01:49 +0100
---
 xen/arch/x86/hvm/hvm.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index f7b3137..28824b7 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -3292,7 +3292,7 @@ int hvm_do_hypercall(struct cpu_user_regs *regs)
     case 4:
     case 2:
         hvm_get_segment_register(curr, x86_seg_ss, &sreg);
-        if ( unlikely(sreg.attr.fields.dpl == 3) )
+        if ( unlikely(sreg.attr.fields.dpl) )
         {
     default:
             regs->eax = -EPERM;
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.2

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