From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Date: Wed, 13 Aug 2014 16:40:38 +0000 (-0400)
Subject: tools/libxc: Set max_elem to zero in xc_lockprof_query_number()
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~4505
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=355ed81e1a6ec3987194023d2538a3c4e5d1619d;p=xen.git

tools/libxc: Set max_elem to zero in xc_lockprof_query_number()

If max_elem is not zero then hypervisor's spinlock_profile_ucopy_elem()
will attempt to copy profile data into user's data buffer. Since this
buffer is explicitly set to (the equivalent of) NULL the copy will fail,
causing xenlockprof to fail as well.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
---

diff --git a/tools/libxc/xc_misc.c b/tools/libxc/xc_misc.c
index 4143de60a3..e253a58b9b 100644
--- a/tools/libxc/xc_misc.c
+++ b/tools/libxc/xc_misc.c
@@ -320,6 +320,7 @@ int xc_lockprof_query_number(xc_interface *xch,
     DECLARE_SYSCTL;
 
     sysctl.cmd = XEN_SYSCTL_lockprof_op;
+    sysctl.u.lockprof_op.max_elem = 0;
     sysctl.u.lockprof_op.cmd = XEN_SYSCTL_LOCKPROF_query;
     set_xen_guest_handle(sysctl.u.lockprof_op.data, HYPERCALL_BUFFER_NULL);