Repository : ssh://git@open-mesh.org/batman-adv
On branch : master
commit 9b8ceef26c697d0c8319748428944c3339a498dc Author: Sven Eckelmann sven@narfation.org Date: Thu Oct 3 17:02:01 2019 +0200
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 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/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: ea6f8d42a595 ("batman-adv: move /proc interface handling to /sys") Signed-off-by: Sven Eckelmann sven@narfation.org
9b8ceef26c697d0c8319748428944c3339a498dc net/batman-adv/bat_iv_ogm.c | 33 +++++++++++++++++++++++++++------ net/batman-adv/types.h | 4 ++-- 2 files changed, 29 insertions(+), 8 deletions(-)
diff --git a/net/batman-adv/bat_iv_ogm.c b/net/batman-adv/bat_iv_ogm.c index d78938e3..e20c3813 100644 --- a/net/batman-adv/bat_iv_ogm.c +++ b/net/batman-adv/bat_iv_ogm.c @@ -29,6 +29,7 @@ #include <linux/random.h> #include <linux/rculist.h> #include <linux/rcupdate.h> +#include <linux/rtnetlink.h> #include <linux/seq_file.h> #include <linux/skbuff.h> #include <linux/slab.h> @@ -193,6 +194,8 @@ static int batadv_iv_ogm_iface_enable(struct batadv_hard_iface *hard_iface) unsigned char *ogm_buff; u32 random_seqno;
+ ASSERT_RTNL(); + /* randomize initial seqno to avoid collision */ get_random_bytes(&random_seqno, sizeof(random_seqno)); atomic_set(&hard_iface->bat_iv.ogm_seqno, random_seqno); @@ -217,6 +220,8 @@ static int batadv_iv_ogm_iface_enable(struct batadv_hard_iface *hard_iface)
static void batadv_iv_ogm_iface_disable(struct batadv_hard_iface *hard_iface) { + ASSERT_RTNL(); + kfree(hard_iface->bat_iv.ogm_buff); hard_iface->bat_iv.ogm_buff = NULL; } @@ -226,6 +231,8 @@ 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;
+ ASSERT_RTNL(); + batadv_ogm_packet = (struct batadv_ogm_packet *)ogm_buff; ether_addr_copy(batadv_ogm_packet->orig, hard_iface->net_dev->dev_addr); @@ -239,6 +246,8 @@ 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;
+ ASSERT_RTNL(); + batadv_ogm_packet = (struct batadv_ogm_packet *)ogm_buff; batadv_ogm_packet->ttl = BATADV_TTL; } @@ -753,6 +762,8 @@ static void batadv_iv_ogm_schedule(struct batadv_hard_iface *hard_iface) u16 tvlv_len = 0; unsigned long send_time;
+ ASSERT_RTNL(); + if (hard_iface->if_status == BATADV_IF_NOT_IN_USE || hard_iface->if_status == BATADV_IF_TO_BE_REMOVED) return; @@ -1643,16 +1654,12 @@ static void batadv_iv_ogm_process(const struct sk_buff *skb, int ogm_offset, batadv_orig_node_put(orig_node); }
-static void batadv_iv_send_outstanding_bat_ogm_packet(struct work_struct *work) +static void +batadv_iv_send_outstanding_forw_packet(struct batadv_forw_packet *forw_packet) { - struct delayed_work *delayed_work; - struct batadv_forw_packet *forw_packet; struct batadv_priv *bat_priv; bool dropped = false;
- delayed_work = to_delayed_work(work); - forw_packet = container_of(delayed_work, struct batadv_forw_packet, - delayed_work); bat_priv = netdev_priv(forw_packet->if_incoming->soft_iface);
if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_DEACTIVATING) { @@ -1681,6 +1688,20 @@ out: batadv_forw_packet_free(forw_packet, dropped); }
+static void batadv_iv_send_outstanding_bat_ogm_packet(struct work_struct *work) +{ + struct delayed_work *delayed_work; + struct batadv_forw_packet *forw_packet; + + delayed_work = to_delayed_work(work); + forw_packet = container_of(delayed_work, struct batadv_forw_packet, + delayed_work); + + rtnl_lock(); + batadv_iv_send_outstanding_forw_packet(forw_packet); + rtnl_unlock(); +} + static int batadv_iv_ogm_receive(struct sk_buff *skb, struct batadv_hard_iface *if_incoming) { diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h index 3eb3150e..282a4650 100644 --- a/net/batman-adv/types.h +++ b/net/batman-adv/types.h @@ -73,10 +73,10 @@ enum batadv_dhcp_recipient { * struct batadv_hard_iface_bat_iv - per hard-interface B.A.T.M.A.N. IV data */ struct batadv_hard_iface_bat_iv { - /** @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 */