From b2ad4e6b24ed0271ca76cb27856def0a701fb778 Mon Sep 17 00:00:00 2001

From: Davide Caratti <davide.caratti@gmail.com>

Date: Wed, 2 Oct 2019 14:08:41 +0200

Subject: [PATCH] D-Bus: Fix P2P NULL dereference after interface removal

When the P2P management interface is deleted, P2P is then disabled and

global->p2p_init_wpa_s is set to NULL. After that, other interfaces can

still trigger P2P functions (like wpas_p2p_find()) using D-Bus. This

makes wpa_supplicant terminate with SIGSEGV, because it dereferences a

NULL pointer. Fix this by adding proper checks, like it's done with

wpa_cli.

CC: Beniamino Galvani <bgalvani@redhat.com>

CC: Benjamin Berg <benjamin@sipsolutions.net>

Reported-by: Vladimir Benes <vbenes@redhat.com>

Signed-off-by: Davide Caratti <davide.caratti@gmail.com>

---

 wpa_supplicant/dbus/dbus_new_handlers_p2p.c | 69 ++++++++++++++++++++-

 1 file changed, 67 insertions(+), 2 deletions(-)

diff --git a/wpa_supplicant/dbus/dbus_new_handlers_p2p.c b/wpa_supplicant/dbus/dbus_new_handlers_p2p.c

index 8cdd88564..19715eb4c 100644

--- a/wpa_supplicant/dbus/dbus_new_handlers_p2p.c

+++ b/wpa_supplicant/dbus/dbus_new_handlers_p2p.c

@@ -40,6 +40,14 @@ static int wpas_dbus_validate_dbus_ipaddr(struct wpa_dbus_dict_entry entry)

 }

+static dbus_bool_t no_p2p_mgmt_interface(DBusError *error)

+{

+	dbus_set_error_const(error, WPAS_DBUS_ERROR_IFACE_UNKNOWN,

+			     "Could not find P2P mgmt interface");

+	return FALSE;

+}

+

+

 /**

  * Parses out the mac address from the peer object path.

  * @peer_path - object path of the form

@@ -78,6 +86,22 @@ wpas_dbus_error_persistent_group_unknown(DBusMessage *message)

 }

+/**

+ * wpas_dbus_error_no_p2p_mgmt_iface - Return a new InterfaceUnknown error

+ * message

+ * @message: Pointer to incoming dbus message this error refers to

+ * Returns: a dbus error message

+ *

+ * Convenience function to create and return an unknown interface error.

+ */

+static DBusMessage * wpas_dbus_error_no_p2p_mgmt_iface(DBusMessage *message)

+{

+	wpa_printf(MSG_DEBUG, "dbus: Could not find P2P mgmt interface");

+	return dbus_message_new_error(message, WPAS_DBUS_ERROR_IFACE_UNKNOWN,

+				      "Could not find P2P mgmt interface");

+}

+

+

 DBusMessage * wpas_dbus_handler_p2p_find(DBusMessage *message,

 					 struct wpa_supplicant *wpa_s)

 {

@@ -145,6 +169,10 @@ DBusMessage * wpas_dbus_handler_p2p_find(DBusMessage *message,

 	}

 	wpa_s = wpa_s->global->p2p_init_wpa_s;

+	if (!wpa_s) {

+		reply = wpas_dbus_error_no_p2p_mgmt_iface(message);

+		goto error_nop2p;

+	}

 	if (wpas_p2p_find(wpa_s, timeout, type, num_req_dev_types,

 			  req_dev_types, NULL, 0, 0, NULL, freq))

@@ -157,8 +185,9 @@ DBusMessage * wpas_dbus_handler_p2p_find(DBusMessage *message,

 error_clear:

 	wpa_dbus_dict_entry_clear(&entry);

 error:

-	os_free(req_dev_types);

 	reply = wpas_dbus_error_invalid_args(message, entry.key);

+error_nop2p:

+	os_free(req_dev_types);

 	return reply;

 }

@@ -166,7 +195,9 @@ error:

 DBusMessage * wpas_dbus_handler_p2p_stop_find(DBusMessage *message,

 					      struct wpa_supplicant *wpa_s)

 {

-	wpas_p2p_stop_find(wpa_s->global->p2p_init_wpa_s);

+	wpa_s = wpa_s->global->p2p_init_wpa_s;

+	if (wpa_s)

+		wpas_p2p_stop_find(wpa_s);

 	return NULL;

 }

@@ -185,6 +216,8 @@ DBusMessage * wpas_dbus_handler_p2p_rejectpeer(DBusMessage *message,

 		return wpas_dbus_error_invalid_args(message, NULL);

 	wpa_s = wpa_s->global->p2p_init_wpa_s;

+	if (!wpa_s)

+		return wpas_dbus_error_no_p2p_mgmt_iface(message);

 	if (wpas_p2p_reject(wpa_s, peer_addr) < 0)

 		return wpas_dbus_error_unknown_error(message,

@@ -204,6 +237,8 @@ DBusMessage * wpas_dbus_handler_p2p_listen(DBusMessage *message,

 		return wpas_dbus_error_no_memory(message);

 	wpa_s = wpa_s->global->p2p_init_wpa_s;

+	if (!wpa_s)

+		return wpas_dbus_error_no_p2p_mgmt_iface(message);

 	if (wpas_p2p_listen(wpa_s, (unsigned int) timeout)) {

 		return dbus_message_new_error(message,

@@ -245,6 +280,8 @@ DBusMessage * wpas_dbus_handler_p2p_extendedlisten(

 	}

 	wpa_s = wpa_s->global->p2p_init_wpa_s;

+	if (!wpa_s)

+		return wpas_dbus_error_no_p2p_mgmt_iface(message);

 	if (wpas_p2p_ext_listen(wpa_s, period, interval))

 		return wpas_dbus_error_unknown_error(

@@ -350,6 +387,10 @@ DBusMessage * wpas_dbus_handler_p2p_group_add(DBusMessage *message,

 	}

 	wpa_s = wpa_s->global->p2p_init_wpa_s;

+	if (!wpa_s) {

+		reply = wpas_dbus_error_no_p2p_mgmt_iface(message);

+		goto out;

+	}

 	if (pg_object_path != NULL) {

 		char *net_id_str;

@@ -433,6 +474,12 @@ static dbus_bool_t wpa_dbus_p2p_check_enabled(struct wpa_supplicant *wpa_s,

 				     "P2P is not available for this interface");

 		return FALSE;

 	}

+	if (!wpa_s->global->p2p_init_wpa_s) {

+		if (out_reply)

+			*out_reply = wpas_dbus_error_no_p2p_mgmt_iface(

+				message);

+		return no_p2p_mgmt_interface(error);

+	}

 	return TRUE;

 }

@@ -822,6 +869,8 @@ DBusMessage * wpas_dbus_handler_p2p_prov_disc_req(DBusMessage *message,

 		return wpas_dbus_error_invalid_args(message, NULL);

 	wpa_s = wpa_s->global->p2p_init_wpa_s;

+	if (!wpa_s)

+		return wpas_dbus_error_no_p2p_mgmt_iface(message);

 	if (wpas_p2p_prov_disc(wpa_s, peer_addr, config_method,

 			       WPAS_P2P_PD_FOR_GO_NEG, NULL) < 0)

@@ -1882,6 +1931,8 @@ dbus_bool_t wpas_dbus_getter_p2p_peer_groups(

 	wpa_s = peer_args->wpa_s;

 	wpa_s = wpa_s->global->p2p_init_wpa_s;

+	if (!wpa_s)

+		return no_p2p_mgmt_interface(error);

 	wpa_s_go = wpas_get_p2p_client_iface(wpa_s, info->p2p_device_addr);

 	if (wpa_s_go) {

@@ -1963,6 +2014,9 @@ dbus_bool_t wpas_dbus_getter_persistent_groups(

 	dbus_bool_t success = FALSE;

 	wpa_s = wpa_s->global->p2p_init_wpa_s;

+	if (!wpa_s)

+		return no_p2p_mgmt_interface(error);

+

 	if (!wpa_s->parent->dbus_new_path)

 		return FALSE;

@@ -2077,6 +2131,11 @@ DBusMessage * wpas_dbus_handler_add_persistent_group(

 	dbus_message_iter_init(message, &iter);

 	wpa_s = wpa_s->global->p2p_init_wpa_s;

+	if (!wpa_s) {

+		reply = wpas_dbus_error_no_p2p_mgmt_iface(message);

+		goto err;

+	}

+

 	if (wpa_s->parent->dbus_new_path)

 		ssid = wpa_config_add_network(wpa_s->conf);

 	if (ssid == NULL) {

@@ -2159,6 +2218,10 @@ DBusMessage * wpas_dbus_handler_remove_persistent_group(

 			      DBUS_TYPE_INVALID);

 	wpa_s = wpa_s->global->p2p_init_wpa_s;

+	if (!wpa_s) {

+		reply = wpas_dbus_error_no_p2p_mgmt_iface(message);

+		goto out;

+	}

 	/*

 	 * Extract the network ID and ensure the network is actually a child of

@@ -2235,6 +2298,8 @@ DBusMessage * wpas_dbus_handler_remove_all_persistent_groups(

 	struct wpa_config *config;

 	wpa_s = wpa_s->global->p2p_init_wpa_s;

+	if (!wpa_s)

+		return wpas_dbus_error_no_p2p_mgmt_iface(message);

 	config = wpa_s->conf;

 	ssid = config->ssid;

-- 

2.26.2