The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable@xxxxxxxxxxxxxxx>. 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