util: Fix stack smashing in virNetDevGetFamilyId

After commit 8708ca01 libvirtd consistently aborts with "stack
 smashing detected" when nodedev driver is initialized.

This is caused by nlmsg_parse() being told that its array of nlattr*
has CTRL_CMD_MAX (10) entries, when in fact it is declared to have
CTRL_ATTR_MAX (8) entries. Since all the entries are initialized to
NULL, the result is that nlmsg_parse is overwriting 2*(sizof(nlattr*))
bytes outside the array.
Signed-off-by: NLaine Stump <laine@laine.org>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

src/util/virnetdev.c

@@ -3183,7 +3183,7 @@ virNetDevGetFamilyId(const char *family_name)
     if (virNetlinkCommand(nl_msg, &resp, &recvbuflen, 0, 0, NETLINK_GENERIC, 0) < 0)
         goto cleanup;
 
-    if (nlmsg_parse(resp, sizeof(struct nlmsghdr), tb, CTRL_CMD_MAX, NULL) < 0) {
+    if (nlmsg_parse(resp, sizeof(struct nlmsghdr), tb, CTRL_ATTR_MAX, NULL) < 0) {
         virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
                        _("malformed netlink response message"));
         goto cleanup;