[Qemu-devel] [PATCH v2] hostmem: Validate host-nodes before setting bitmap

[Eduardo Habkost <ehabkost@redhat.com>]

host_memory_backend_set_host_nodes() was not validating
host-nodes before writing to backend->host_nodes, making QEMU
write beyond the end of the bitmap.

Fix the crash and add a simple regression test for the fix.

While at it, fix memory leak of the list returned by
visit_type_uint16List().

Reported-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
Changes v1 -> v2:
* Remove extra `l = l->next` statement
  (reported by Stefano Garzarella)
* Fix (existing) leak of `host_nodes`
  (reported by Markus Armbruster)
---
 backends/hostmem.c                   | 17 +++++++++----
 tests/acceptance/host-nodes-limit.py | 36 ++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+), 4 deletions(-)
 create mode 100644 tests/acceptance/host-nodes-limit.py

diff --git a/backends/hostmem.c b/backends/hostmem.c
index 1a89342039..af800284e0 100644
--- a/backends/hostmem.c
+++ b/backends/hostmem.c
@@ -103,14 +103,23 @@ host_memory_backend_set_host_nodes(Object *obj, Visitor *v, const char *name,
 {
 #ifdef CONFIG_NUMA
     HostMemoryBackend *backend = MEMORY_BACKEND(obj);
-    uint16List *l = NULL;
+    uint16List *l, *host_nodes = NULL;
 
-    visit_type_uint16List(v, name, &l, errp);
+    visit_type_uint16List(v, name, &host_nodes, errp);
 
-    while (l) {
+    for (l = host_nodes; l; l = l->next) {
+        if (l->value >= MAX_NODES) {
+            error_setg(errp, "Invalid host-nodes value: %d", l->value);
+            goto out;
+        }
+    }
+
+    for (l = host_nodes; l; l = l->next) {
         bitmap_set(backend->host_nodes, l->value, 1);
-        l = l->next;
     }
+
+out:
+    qapi_free_uint16List(host_nodes);
 #else
     error_setg(errp, "NUMA node binding are not supported by this QEMU");
 #endif
diff --git a/tests/acceptance/host-nodes-limit.py b/tests/acceptance/host-nodes-limit.py
new file mode 100644
index 0000000000..e803e10104
--- /dev/null
+++ b/tests/acceptance/host-nodes-limit.py
@@ -0,0 +1,36 @@
+# Regression test for host-nodes limit validation
+#
+# Copyright (c) 2018 Red Hat, Inc.
+#
+# Author:
+#  Eduardo Habkost <ehabkost@redhat.com>
+#
+# This work is licensed under the terms of the GNU GPL, version 2 or
+# later.  See the COPYING file in the top-level directory.
+
+from avocado_qemu import Test
+from subprocess import Popen, PIPE
+
+MAX_NODES = 128
+
+class HostNodesValidation(Test):
+    def test_large_host_nodes(self):
+        p = Popen([self.qemu_bin, '-display', 'none', '-nodefaults',
+                   '-object', 'memory-backend-ram,id=m0,'
+                              'size=4096,host-nodes=%d' % (MAX_NODES)],
+                  stderr=PIPE, stdout=PIPE)
+        stdout,stderr = p.communicate()
+
+        self.assertIn(b'Invalid host-nodes', stderr)
+        self.assertEquals(stdout, b'')
+        self.assertEquals(p.returncode, 1)
+
+    def test_valid_host_nodes(self):
+        p = Popen([self.qemu_bin, '-display', 'none', '-nodefaults',
+                   '-object', 'memory-backend-ram,id=m0,'
+                              'size=4096,host-nodes=%d' % (MAX_NODES - 1)],
+                  stderr=PIPE, stdout=PIPE)
+        stdout,stderr = p.communicate()
+
+        self.assertIn(b'host-nodes must be empty', stderr)
+        self.assertEquals(p.returncode, 1)
-- 
2.18.0.rc1.1.g3f1ff2140