From a8d23cbbf6c9f515ed678204ad2962be7c336344 Mon Sep 17 00:00:00 2001 From: Sven Eckelmann Date: Thu, 3 Oct 2019 17:02:01 +0200 Subject: [PATCH 1/2] 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 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: 0da0035942d4 ("batman-adv: OGMv2 - add basic infrastructure") Signed-off-by: Sven Eckelmann Signed-off-by: Simon Wunderlich --- net/batman-adv/bat_v_ogm.c | 41 ++++++++++++++++++++++++++++++-------- net/batman-adv/types.h | 4 ++++ 2 files changed, 37 insertions(+), 8 deletions(-) diff --git a/net/batman-adv/bat_v_ogm.c b/net/batman-adv/bat_v_ogm.c index dc4f7430cb5a..8033f24f506c 100644 --- a/net/batman-adv/bat_v_ogm.c +++ b/net/batman-adv/bat_v_ogm.c @@ -18,6 +18,7 @@ #include #include #include +#include #include #include #include @@ -256,14 +257,12 @@ static void batadv_v_ogm_queue_on_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; @@ -271,8 +270,7 @@ 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); + lockdep_assert_held(&bat_priv->bat_v.ogm_buff_mutex); if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_DEACTIVATING) goto out; @@ -363,6 +361,23 @@ 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; + + bat_v = container_of(work, struct batadv_priv_bat_v, ogm_wq.work); + bat_priv = container_of(bat_v, struct batadv_priv, bat_v); + + mutex_lock(&bat_priv->bat_v.ogm_buff_mutex); + batadv_v_ogm_send_softif(bat_priv); + mutex_unlock(&bat_priv->bat_v.ogm_buff_mutex); +} + /** * batadv_v_ogm_aggr_work() - OGM queue periodic task per interface * @work: work queue item @@ -424,11 +439,15 @@ 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; + mutex_lock(&bat_priv->bat_v.ogm_buff_mutex); if (!bat_priv->bat_v.ogm_buff) - return; + goto unlock; ogm_packet = (struct batadv_ogm2_packet *)bat_priv->bat_v.ogm_buff; ether_addr_copy(ogm_packet->orig, primary_iface->net_dev->dev_addr); + +unlock: + mutex_unlock(&bat_priv->bat_v.ogm_buff_mutex); } /** @@ -1050,6 +1069,8 @@ int batadv_v_ogm_init(struct batadv_priv *bat_priv) atomic_set(&bat_priv->bat_v.ogm_seqno, random_seqno); INIT_DELAYED_WORK(&bat_priv->bat_v.ogm_wq, batadv_v_ogm_send); + mutex_init(&bat_priv->bat_v.ogm_buff_mutex); + return 0; } @@ -1061,7 +1082,11 @@ void batadv_v_ogm_free(struct batadv_priv *bat_priv) { cancel_delayed_work_sync(&bat_priv->bat_v.ogm_wq); + mutex_lock(&bat_priv->bat_v.ogm_buff_mutex); + kfree(bat_priv->bat_v.ogm_buff); bat_priv->bat_v.ogm_buff = NULL; bat_priv->bat_v.ogm_buff_len = 0; + + mutex_unlock(&bat_priv->bat_v.ogm_buff_mutex); } diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h index be7c02aa91e2..a9fb7b17f557 100644 --- a/net/batman-adv/types.h +++ b/net/batman-adv/types.h @@ -17,6 +17,7 @@ #include #include #include +#include #include #include #include /* for linux/wait.h */ @@ -1539,6 +1540,9 @@ struct batadv_priv_bat_v { /** @ogm_seqno: OGM sequence number - used to identify each OGM */ atomic_t ogm_seqno; + /** @ogm_buff_mutex: lock protecting ogm_buff and ogm_buff_len */ + struct mutex ogm_buff_mutex; + /** @ogm_wq: workqueue used to schedule OGM transmissions */ struct delayed_work ogm_wq; }; From 40e220b4218bb3d278e5e8cc04ccdfd1c7ff8307 Mon Sep 17 00:00:00 2001 From: Sven Eckelmann Date: Thu, 3 Oct 2019 17:02:01 +0200 Subject: [PATCH 2/2] batman-adv: Avoid free/alloc race when handling OGM buffer Each slave interface of an B.A.T.M.A.N. IV virtual interface has an OGM packet buffer which is initialized using data from 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/freed data is sent out or functions modifying the OGM buffer try to access already freed memory regions. Reported-by: syzbot+0cc629f19ccb8534935b@syzkaller.appspotmail.com Fixes: c6c8fea29769 ("net: Add batman-adv meshing protocol") Signed-off-by: Sven Eckelmann Signed-off-by: Simon Wunderlich --- net/batman-adv/bat_iv_ogm.c | 61 ++++++++++++++++++++++++++++----- net/batman-adv/hard-interface.c | 2 ++ net/batman-adv/types.h | 3 ++ 3 files changed, 57 insertions(+), 9 deletions(-) diff --git a/net/batman-adv/bat_iv_ogm.c b/net/batman-adv/bat_iv_ogm.c index d78938e3e008..5b0b20e6da95 100644 --- a/net/batman-adv/bat_iv_ogm.c +++ b/net/batman-adv/bat_iv_ogm.c @@ -22,6 +22,8 @@ #include #include #include +#include +#include #include #include #include @@ -193,14 +195,18 @@ static int batadv_iv_ogm_iface_enable(struct batadv_hard_iface *hard_iface) unsigned char *ogm_buff; u32 random_seqno; + mutex_lock(&hard_iface->bat_iv.ogm_buff_mutex); + /* randomize initial seqno to avoid collision */ get_random_bytes(&random_seqno, sizeof(random_seqno)); atomic_set(&hard_iface->bat_iv.ogm_seqno, random_seqno); hard_iface->bat_iv.ogm_buff_len = BATADV_OGM_HLEN; ogm_buff = kmalloc(hard_iface->bat_iv.ogm_buff_len, GFP_ATOMIC); - if (!ogm_buff) + if (!ogm_buff) { + mutex_unlock(&hard_iface->bat_iv.ogm_buff_mutex); return -ENOMEM; + } hard_iface->bat_iv.ogm_buff = ogm_buff; @@ -212,35 +218,59 @@ static int batadv_iv_ogm_iface_enable(struct batadv_hard_iface *hard_iface) batadv_ogm_packet->reserved = 0; batadv_ogm_packet->tq = BATADV_TQ_MAX_VALUE; + mutex_unlock(&hard_iface->bat_iv.ogm_buff_mutex); + return 0; } static void batadv_iv_ogm_iface_disable(struct batadv_hard_iface *hard_iface) { + mutex_lock(&hard_iface->bat_iv.ogm_buff_mutex); + kfree(hard_iface->bat_iv.ogm_buff); hard_iface->bat_iv.ogm_buff = NULL; + + mutex_unlock(&hard_iface->bat_iv.ogm_buff_mutex); } static void batadv_iv_ogm_iface_update_mac(struct batadv_hard_iface *hard_iface) { struct batadv_ogm_packet *batadv_ogm_packet; - unsigned char *ogm_buff = hard_iface->bat_iv.ogm_buff; + void *ogm_buff; - batadv_ogm_packet = (struct batadv_ogm_packet *)ogm_buff; + mutex_lock(&hard_iface->bat_iv.ogm_buff_mutex); + + ogm_buff = hard_iface->bat_iv.ogm_buff; + if (!ogm_buff) + goto unlock; + + batadv_ogm_packet = ogm_buff; ether_addr_copy(batadv_ogm_packet->orig, hard_iface->net_dev->dev_addr); ether_addr_copy(batadv_ogm_packet->prev_sender, hard_iface->net_dev->dev_addr); + +unlock: + mutex_unlock(&hard_iface->bat_iv.ogm_buff_mutex); } static void batadv_iv_ogm_primary_iface_set(struct batadv_hard_iface *hard_iface) { struct batadv_ogm_packet *batadv_ogm_packet; - unsigned char *ogm_buff = hard_iface->bat_iv.ogm_buff; + void *ogm_buff; - batadv_ogm_packet = (struct batadv_ogm_packet *)ogm_buff; + mutex_lock(&hard_iface->bat_iv.ogm_buff_mutex); + + ogm_buff = hard_iface->bat_iv.ogm_buff; + if (!ogm_buff) + goto unlock; + + batadv_ogm_packet = ogm_buff; batadv_ogm_packet->ttl = BATADV_TTL; + +unlock: + mutex_unlock(&hard_iface->bat_iv.ogm_buff_mutex); } /* when do we schedule our own ogm to be sent */ @@ -742,7 +772,11 @@ batadv_iv_ogm_slide_own_bcast_window(struct batadv_hard_iface *hard_iface) } } -static void batadv_iv_ogm_schedule(struct batadv_hard_iface *hard_iface) +/** + * batadv_iv_ogm_schedule_buff() - schedule submission of hardif ogm buffer + * @hard_iface: interface whose ogm buffer should be transmitted + */ +static void batadv_iv_ogm_schedule_buff(struct batadv_hard_iface *hard_iface) { struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface); unsigned char **ogm_buff = &hard_iface->bat_iv.ogm_buff; @@ -753,9 +787,7 @@ static void batadv_iv_ogm_schedule(struct batadv_hard_iface *hard_iface) u16 tvlv_len = 0; unsigned long send_time; - if (hard_iface->if_status == BATADV_IF_NOT_IN_USE || - hard_iface->if_status == BATADV_IF_TO_BE_REMOVED) - return; + lockdep_assert_held(&hard_iface->bat_iv.ogm_buff_mutex); /* the interface gets activated here to avoid race conditions between * the moment of activating the interface in @@ -823,6 +855,17 @@ out: batadv_hardif_put(primary_if); } +static void batadv_iv_ogm_schedule(struct batadv_hard_iface *hard_iface) +{ + if (hard_iface->if_status == BATADV_IF_NOT_IN_USE || + hard_iface->if_status == BATADV_IF_TO_BE_REMOVED) + return; + + mutex_lock(&hard_iface->bat_iv.ogm_buff_mutex); + batadv_iv_ogm_schedule_buff(hard_iface); + mutex_unlock(&hard_iface->bat_iv.ogm_buff_mutex); +} + /** * batadv_iv_orig_ifinfo_sum() - Get bcast_own sum for originator over iterface * @orig_node: originator which reproadcasted the OGMs directly diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c index c90e47342bb0..afb52282d5bd 100644 --- a/net/batman-adv/hard-interface.c +++ b/net/batman-adv/hard-interface.c @@ -18,6 +18,7 @@ #include #include #include +#include #include #include #include @@ -929,6 +930,7 @@ batadv_hardif_add_interface(struct net_device *net_dev) INIT_LIST_HEAD(&hard_iface->list); INIT_HLIST_HEAD(&hard_iface->neigh_list); + mutex_init(&hard_iface->bat_iv.ogm_buff_mutex); spin_lock_init(&hard_iface->neigh_list_lock); kref_init(&hard_iface->refcount); diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h index a9fb7b17f557..4d7f1baee7b7 100644 --- a/net/batman-adv/types.h +++ b/net/batman-adv/types.h @@ -82,6 +82,9 @@ struct batadv_hard_iface_bat_iv { /** @ogm_seqno: OGM sequence number - used to identify each OGM */ atomic_t ogm_seqno; + + /** @ogm_buff_mutex: lock protecting ogm_buff and ogm_buff_len */ + struct mutex ogm_buff_mutex; }; /**