[PATCH 2/2] shared/compat: Fix memory handling of nm_setting_vpn_get_*_keys (v2)

["Jan Alexander Steffens (heftig)" <jan steffens gmail com>]

The compat implementations return a (transfer none) strv instead of a
(transfer container) one. This has caused double frees in nm-applet:
https://bugs.archlinux.org/task/56772

We still need to copy the keys because nm_setting_vpn_foreach_* provides
us with copies that are freed after the iteration.

Fix this by handing out a duplicate of the array.

Fixes: 272439cb2077a889485dd195bb6b99ca91d3e3bf
---
 shared/nm-utils/nm-compat.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/shared/nm-utils/nm-compat.c b/shared/nm-utils/nm-compat.c
index 22ab675de8373639..b470e804c08441b4 100644
--- a/shared/nm-utils/nm-compat.c
+++ b/shared/nm-utils/nm-compat.c
@@ -44,25 +44,32 @@ _get_keys (NMSettingVpn *setting,
 
        nm_assert (NM_IS_SETTING_VPN (setting));
 
-       a = g_ptr_array_new ();
+       if (is_secrets)
+               len = nm_setting_vpn_get_num_secrets (setting);
+       else
+               len = nm_setting_vpn_get_num_data_items (setting);
+
+       a = g_ptr_array_new_full (len + 1, (GDestroyNotify) g_free);
+
        if (is_secrets)
                nm_setting_vpn_foreach_secret (setting, _get_keys_cb, a);
        else
                nm_setting_vpn_foreach_data_item (setting, _get_keys_cb, a);
+
        len = a->len;
 
-       if (a->len) {
+       if (len) {
                g_ptr_array_sort (a, nm_strcmp_p);
                g_ptr_array_add (a, NULL);
-               keys = (const char **) g_ptr_array_free (g_steal_pointer (&a), FALSE);
+               keys = g_memdup (a->pdata, a->len * sizeof *keys);
 
                /* we need to cache the keys *somewhere*. */
                g_object_set_qdata_full (G_OBJECT (setting),
                                         is_secrets
                                         ? NM_CACHED_QUARK ("libnm._nm_setting_vpn_get_secret_keys")
                                         : NM_CACHED_QUARK ("libnm._nm_setting_vpn_get_data_keys"),
-                                        keys,
-                                        (GDestroyNotify) g_strfreev);
+                                        g_ptr_array_ref (a),
+                                        (GDestroyNotify) g_ptr_array_unref);
        }
 
        NM_SET_OUT (out_length, len);
-- 
2.15.1