[Xen-changelog] [xen stable-4.2] libxc: limit cpu values when setting vcpu affinity

[patchbot@xxxxxxx]

commit 34e2c78baa7eff6369595adc7e51e70a4a0c8727
Author:     Petr Matousek <pmatouse@xxxxxxxxxx>
AuthorDate: Fri May 31 12:24:18 2013 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri May 31 12:24:18 2013 +0200

    libxc: limit cpu values when setting vcpu affinity
    
    When support for pinning more than 64 cpus was added, check for cpu
    out-of-range values was removed. This can lead to subsequent
    out-of-bounds cpumap array accesses in case the cpu number is higher
    than the actual count.
    
    This patch returns the check.
    
    This is CVE-2013-2072 / XSA-56
    
    Signed-off-by: Petr Matousek <pmatouse@xxxxxxxxxx>
    master commit: 41abbadef60e5fccdfd688579dd458f7f7887cf5
    master date: 2013-05-29 15:49:22 +0100
---
 tools/python/xen/lowlevel/xc/xc.c |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/tools/python/xen/lowlevel/xc/xc.c 
b/tools/python/xen/lowlevel/xc/xc.c
index 7c89756..540de61 100644
--- a/tools/python/xen/lowlevel/xc/xc.c
+++ b/tools/python/xen/lowlevel/xc/xc.c
@@ -228,6 +228,7 @@ static PyObject *pyxc_vcpu_setaffinity(XcObject *self,
     int vcpu = 0, i;
     xc_cpumap_t cpumap;
     PyObject *cpulist = NULL;
+    int nr_cpus;
 
     static char *kwd_list[] = { "domid", "vcpu", "cpumap", NULL };
 
@@ -235,6 +236,10 @@ static PyObject *pyxc_vcpu_setaffinity(XcObject *self,
                                       &dom, &vcpu, &cpulist) )
         return NULL;
 
+    nr_cpus = xc_get_max_cpus(self->xc_handle);
+    if ( nr_cpus == 0 )
+        return pyxc_error_to_exception(self->xc_handle);
+
     cpumap = xc_cpumap_alloc(self->xc_handle);
     if(cpumap == NULL)
         return pyxc_error_to_exception(self->xc_handle);
@@ -244,6 +249,13 @@ static PyObject *pyxc_vcpu_setaffinity(XcObject *self,
         for ( i = 0; i < PyList_Size(cpulist); i++ ) 
         {
             long cpu = PyInt_AsLong(PyList_GetItem(cpulist, i));
+            if ( cpu < 0 || cpu >= nr_cpus )
+            {
+                free(cpumap);
+                errno = EINVAL;
+                PyErr_SetFromErrno(xc_error_obj);
+                return NULL;
+            }
             cpumap[cpu / 8] |= 1 << (cpu % 8);
         }
     }
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.2

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