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Groups > linux.kernel > #1673519

[PATCH] x86/xen: allow userspace access during hypercalls

From Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Newsgroups linux.kernel
Subject [PATCH] x86/xen: allow userspace access during hypercalls
Date 2017-06-23 14:50 +0200
Message-ID <tVwca-2bn-11@gated-at.bofh.it> (permalink)
Organization Invisible Things Lab

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Userspace application can do a hypercall through /dev/xen/privcmd, and
some for some hypercalls argument is a pointers to user-provided
structure. When SMAP is supported and enabled, hypervisor can't access.
So, lets allow it.

Cc: stable@vger.kernel.org
Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
---
 arch/x86/include/asm/xen/hypercall.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/include/asm/xen/hypercall.h b/arch/x86/include/asm/xen/hypercall.h
index f6d20f6..a1d2c5d 100644
--- a/arch/x86/include/asm/xen/hypercall.h
+++ b/arch/x86/include/asm/xen/hypercall.h
@@ -43,6 +43,7 @@
 
 #include <asm/page.h>
 #include <asm/pgtable.h>
+#include <asm/smap.h>
 
 #include <xen/interface/xen.h>
 #include <xen/interface/sched.h>
@@ -214,10 +215,12 @@ privcmd_call(unsigned call,
 	__HYPERCALL_DECLS;
 	__HYPERCALL_5ARG(a1, a2, a3, a4, a5);
 
+	stac();
 	asm volatile("call *%[call]"
 		     : __HYPERCALL_5PARAM
 		     : [call] "a" (&hypercall_page[call])
 		     : __HYPERCALL_CLOBBER5);
+	clac();
 
 	return (long)__res;
 }
-- 
2.7.4

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[PATCH] x86/xen: allow userspace access during hypercalls Marek Marczykowski-Górecki          <marmarek@invisiblethingslab.com> - 2017-06-23 14:50 +0200
  Re: [PATCH] x86/xen: allow userspace access during hypercalls Juergen Groß <jgross@suse.com> - 2017-06-26 14:10 +0200
    Re: [PATCH] x86/xen: allow userspace access during hypercalls Marek Marczykowski-Górecki          <marmarek@invisiblethingslab.com> - 2017-06-26 14:50 +0200
      Re: [PATCH v2] x86/xen: allow userspace access during hypercalls Juergen Groß <jgross@suse.com> - 2017-06-26 15:00 +0200
      [PATCH v2] x86/xen: allow userspace access during hypercalls Marek Marczykowski-Górecki          <marmarek@invisiblethingslab.com> - 2017-06-26 15:00 +0200
        Re: [PATCH v2] x86/xen: allow userspace access during hypercalls Juergen Gross <jgross@suse.com> - 2017-07-03 13:30 +0200
      RE: [Xen-devel] [PATCH] x86/xen: allow userspace access during         hypercalls Paul Durrant <Paul.Durrant@citrix.com> - 2017-06-26 15:20 +0200
        RE: [Xen-devel] [PATCH] x86/xen: allow userspace access during  hypercalls Paul Durrant <Paul.Durrant@citrix.com> - 2017-06-26 15:30 +0200
        Re: [Xen-devel] [PATCH] x86/xen: allow userspace access during  hypercalls 'Marek Marczykowski-Górecki'          <marmarek@invisiblethingslab.com> - 2017-06-26 15:30 +0200

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