--- /dev/null
+From: Sven Eckelmann <sven@narfation.org>
+Date: Thu, 3 Oct 2019 17:02:01 +0200
+Subject: 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>
+
+Origin: upstream, https://git.open-mesh.org/batman-adv.git/commit/9b8ceef26c697d0c8319748428944c3339a498dc
+
+diff --git a/net/batman-adv/bat_iv_ogm.c b/net/batman-adv/bat_iv_ogm.c
+index 5afc4e9646d622c6f924d4610ac58eb77404b37a..54c5be029b7418bc97d87e7642e258bfed120874 100644
+--- a/net/batman-adv/bat_iv_ogm.c
++++ b/net/batman-adv/bat_iv_ogm.c
+@@ -41,6 +41,7 @@
+ #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>
+@@ -366,6 +367,8 @@ 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);
+@@ -390,6 +393,8 @@ 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;
+ }
+@@ -399,6 +404,8 @@ 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);
+@@ -412,6 +419,8 @@ 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;
+ }
+@@ -923,6 +932,8 @@ 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;
+@@ -1777,16 +1788,12 @@ 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) {
+@@ -1815,6 +1822,20 @@ 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 bf33f04e055bbf288ce6800d0b93da1b4cd9b70d..8906e551c85991e6b085108cf6f2b734b48fc231 100644
+--- a/net/batman-adv/types.h
++++ b/net/batman-adv/types.h
+@@ -78,8 +78,8 @@ enum batadv_dhcp_recipient {
+
+ /**
+ * struct batadv_hard_iface_bat_iv - per hard-interface B.A.T.M.A.N. IV data
+- * @ogm_buff: buffer holding the OGM packet
+- * @ogm_buff_len: length of the OGM packet buffer
++ * @ogm_buff: buffer holding the OGM packet. rtnl protected
++ * @ogm_buff_len: length of the OGM packet buffer. rtnl protected
+ * @ogm_seqno: OGM sequence number - used to identify each OGM
+ */
+ struct batadv_hard_iface_bat_iv {