The patch below was submitted to be applied to the 4.12-stable tree.
I fail to see how this patch meets the stable kernel rules as found at
Documentation/process/stable_kernel_rules.rst.
I could be totally wrong, and if so, please respond to
<stable@xxxxxxxxxxxxxxx> and let me know why this patch should be
applied. Otherwise, it is now dropped from my patch queues, never to be
seen again.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>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: [PATCH] x86/xen: allow userspace access during hypercalls
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
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>
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
diff --git a/arch/x86/include/asm/xen/hypercall.h b/arch/x86/include/asm/xen/hypercall.h
index 7a4db5fefd15..11071fcd630e 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>
@@ -216,10 +217,12 @@ 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;
}
@@ -478,7 +481,11 @@ static inline int
HYPERVISOR_dm_op(
domid_t dom, unsigned int nr_bufs, struct xen_dm_op_buf *bufs)
{
- return _hypercall3(int, dm_op, dom, nr_bufs, bufs);
+ int ret;
+ stac();
+ ret = _hypercall3(int, dm_op, dom, nr_bufs, bufs);
+ clac();
+ return ret;
}
static inline void