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x86/xen: allow userspace access during hypercalls

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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@vger.kernel.org
Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
[HYPERVISOR_dm_op dropped - not present until 4.11]
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Marek Marczykowski-Górecki 2017-06-26 14:49:46 +02:00 committed by Greg Kroah-Hartman
parent 78dce99f54
commit 5c7c179eb9
1 changed files with 3 additions and 0 deletions
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3
arch/x86/include/asm/xen/hypercall.h
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@ -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;
}