This is a note to let you know that I've just added the patch titled
x86/xen: allow userspace access during hypercalls
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-xen-allow-userspace-access-during-hypercalls.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From c54590cac51db8ab5fd30156bdaba34af915e629 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?=
<marmarek@xxxxxxxxxxxxxxxxxxxxxx>
Date: Mon, 26 Jun 2017 14:49:46 +0200
Subject: x86/xen: allow userspace access during hypercalls
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From: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
commit c54590cac51db8ab5fd30156bdaba34af915e629 upstream.
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.
The same applies to HYPERVISOR_dm_op, where additionally privcmd driver
carefully verify buffer addresses.
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
[HYPERVISOR_dm_op dropped - not present until 4.11]
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/include/asm/xen/hypercall.h | 3 +++
1 file changed, 3 insertions(+)
--- 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>
@@ -213,10 +214,12 @@ 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;
}
Patches currently in stable-queue which might be from marmarek@xxxxxxxxxxxxxxxxxxxxxx are
queue-4.4/x86-xen-allow-userspace-access-during-hypercalls.patch