On 29.11.18 19:57, Eduardo Habkost wrote:
> 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.
>
> Reported-by: Markus Armbruster <arm...@redhat.com>
> Signed-off-by: Eduardo Habkost <ehabk...@redhat.com>
> ---
> backends/hostmem.c | 13 +++++++---
> tests/acceptance/host-nodes-limit.py | 36 ++++++++++++++++++++++++++++
> 2 files changed, 46 insertions(+), 3 deletions(-)
> create mode 100644 tests/acceptance/host-nodes-limit.py
>
> diff --git a/backends/hostmem.c b/backends/hostmem.c
> index 1a89342039..ef199d32fd 100644
> --- a/backends/hostmem.c
> +++ b/backends/hostmem.c
> @@ -103,11 +103,18 @@ 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);
> +
> + for (l = host_nodes; l; l = l->next) {
> + if (l->value >= MAX_NODES) {
> + error_setg(errp, "Invalid host-nodes value: %d", l->value);
> + return;
> + }
> + }
>
An alternative would be to use a temporary bitmap (on the stack)
instead and copy it only on success. E.g.
for (l = host_nodes; l; l = l->next) {
if (l->value >= MAX_NODE) {
error_setg(&local_err, "Invalid host-nodes value: %d", l->value);
break;
}
bitmap_set(tmp, l->value, 1);
}
if (!local_err) {
bitmap_copy(backend->host_nodes, tmp, MAX_NODE);
}
error_propagate...
free...
> - while (l) {
> + for (l = host_nodes; l; l = l->next) {
> bitmap_set(backend->host_nodes, l->value, 1);
> l = l->next;
> }
> 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 <ehabk...@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)
>
--
Thanks,
David / dhildenb
