Repository : ssh://git@open-mesh.org/batman-adv

On branch : master

commit 14ee24576213ff02272b7f8d975c7c61d5448aa2 Author: Sven Eckelmann sven@narfation.org Date: Thu Oct 3 17:02:01 2019 +0200

batman-adv: Avoid free/alloc race when handling OGM2 buffer

A B.A.T.M.A.N. V virtual interface has an OGM2 packet buffer which is initialized using data from the RTNL lock protected netdevice notifier and other rtnetlink related hooks. It is sent regularly via various slave interfaces of the batadv virtual interface and in this process also modified (realloced) to integrate additional state information via TVLV containers.

It must be avoided that the worker item is executed without a common lock with the netdevice notifier/rtnetlink helpers. Otherwise it can either happen that half modified data is sent out or the functions modifying the OGM2 buffer try to access already freed memory regions.

Fixes: 632835348e65 ("batman-adv: OGMv2 - add basic infrastructure") Signed-off-by: Sven Eckelmann sven@narfation.org

14ee24576213ff02272b7f8d975c7c61d5448aa2 net/batman-adv/bat_v_ogm.c | 32 +++++++++++++++++++++++++------- net/batman-adv/types.h | 4 ++-- 2 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/net/batman-adv/bat_v_ogm.c b/net/batman-adv/bat_v_ogm.c index bc06e3cd..034bdc5e 100644 --- a/net/batman-adv/bat_v_ogm.c +++ b/net/batman-adv/bat_v_ogm.c @@ -21,6 +21,7 @@ #include <linux/random.h> #include <linux/rculist.h> #include <linux/rcupdate.h> +#include <linux/rtnetlink.h> #include <linux/skbuff.h> #include <linux/slab.h> #include <linux/stddef.h> @@ -116,14 +117,12 @@ static void batadv_v_ogm_send_to_if(struct sk_buff *skb, }

/** - * batadv_v_ogm_send() - periodic worker broadcasting the own OGM - * @work: work queue item + * batadv_v_ogm_send_softif() - periodic worker broadcasting the own OGM + * @bat_priv: the bat priv with all the soft interface information */ -static void batadv_v_ogm_send(struct work_struct *work) +static void batadv_v_ogm_send_softif(struct batadv_priv *bat_priv) { struct batadv_hard_iface *hard_iface; - struct batadv_priv_bat_v *bat_v; - struct batadv_priv *bat_priv; struct batadv_ogm2_packet *ogm_packet; struct sk_buff *skb, *skb_tmp; unsigned char *ogm_buff; @@ -131,8 +130,7 @@ static void batadv_v_ogm_send(struct work_struct *work) u16 tvlv_len = 0; int ret;

- bat_v = container_of(work, struct batadv_priv_bat_v, ogm_wq.work); - bat_priv = container_of(bat_v, struct batadv_priv, bat_v); + ASSERT_RTNL();

if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_DEACTIVATING) goto out; @@ -223,6 +221,22 @@ out: return; }

+/** + * batadv_v_ogm_send() - periodic worker broadcasting the own OGM + * @work: work queue item + */ +static void batadv_v_ogm_send(struct work_struct *work) +{ + struct batadv_priv_bat_v *bat_v; + struct batadv_priv *bat_priv; + + rtnl_lock(); + bat_v = container_of(work, struct batadv_priv_bat_v, ogm_wq.work); + bat_priv = container_of(bat_v, struct batadv_priv, bat_v); + batadv_v_ogm_send_softif(bat_priv); + rtnl_unlock(); +} + /** * batadv_v_ogm_iface_enable() - prepare an interface for B.A.T.M.A.N. V * @hard_iface: the interface to prepare @@ -249,6 +263,8 @@ void batadv_v_ogm_primary_iface_set(struct batadv_hard_iface *primary_iface) struct batadv_priv *bat_priv = netdev_priv(primary_iface->soft_iface); struct batadv_ogm2_packet *ogm_packet;

+ ASSERT_RTNL(); + if (!bat_priv->bat_v.ogm_buff) return;

@@ -857,6 +873,8 @@ int batadv_v_ogm_init(struct batadv_priv *bat_priv) unsigned char *ogm_buff; u32 random_seqno;

+ ASSERT_RTNL(); + bat_priv->bat_v.ogm_buff_len = BATADV_OGM2_HLEN; ogm_buff = kzalloc(bat_priv->bat_v.ogm_buff_len, GFP_ATOMIC); if (!ogm_buff) diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h index 6ae139d7..3eb3150e 100644 --- a/net/batman-adv/types.h +++ b/net/batman-adv/types.h @@ -1518,10 +1518,10 @@ struct batadv_softif_vlan { * struct batadv_priv_bat_v - B.A.T.M.A.N. V per soft-interface private data */ struct batadv_priv_bat_v { - /** @ogm_buff: buffer holding the OGM packet */ + /** @ogm_buff: buffer holding the OGM packet. rtnl protected */ unsigned char *ogm_buff;

- /** @ogm_buff_len: length of the OGM packet buffer */ + /** @ogm_buff_len: length of the OGM packet buffer. rtnl protected */ int ogm_buff_len;

/** @ogm_seqno: OGM sequence number - used to identify each OGM */