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openwrt-routing/batman-adv/patches/0014-batman-adv-Avoid-OGM-w...

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From: Sven Eckelmann <sven@narfation.org>
Date: Sun, 13 Oct 2019 21:03:07 +0200
Subject: batman-adv: Avoid OGM workqueue synchronous cancel deadlock
batadv_forw_packet_list_free can be called when an interface is being
disabled. Under this circumstance, the rntl_lock will be held and while it
calls cancel_delayed_work_sync.
cancel_delayed_work_sync will stop the execution of the current context
when the work item is currently processed. It can now happen that the
cancel_delayed_work_sync was called when rtnl_lock was already called in
batadv_iv_send_outstanding_bat_ogm_packet or when it was in the process of
calling it. In this case, batadv_iv_send_outstanding_bat_ogm_packet waits
for the lock and cancel_delayed_work_sync (which holds the rtnl_lock) is
waiting for batadv_iv_send_outstanding_bat_ogm_packet to finish.
This can only be avoided by not using (conflicting) blocking locks while
cancel_delayed_work_sync is called. It also has the benefit that the
ogm scheduling functionality can avoid unnecessary delays which can be
introduced by a global lock.
Fixes: 9b8ceef26c69 ("batman-adv: Avoid free/alloc race when handling OGM buffer")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Origin: upstream, https://git.open-mesh.org/batman-adv.git/commit/d3be478f1aa27b47f61c4a62e18eb063d47c9168
--- a/net/batman-adv/bat_iv_ogm.c
+++ b/net/batman-adv/bat_iv_ogm.c
@@ -22,6 +22,8 @@
#include <linux/kernel.h>
#include <linux/kref.h>
#include <linux/list.h>
+#include <linux/lockdep.h>
+#include <linux/mutex.h>
#include <linux/netdevice.h>
#include <linux/netlink.h>
#include <linux/pkt_sched.h>
@@ -29,7 +31,6 @@
#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>
@@ -194,7 +195,7 @@ static int batadv_iv_ogm_iface_enable(st
unsigned char *ogm_buff;
u32 random_seqno;
- ASSERT_RTNL();
+ mutex_lock(&hard_iface->bat_iv.ogm_buff_mutex);
/* randomize initial seqno to avoid collision */
get_random_bytes(&random_seqno, sizeof(random_seqno));
@@ -202,8 +203,10 @@ static int batadv_iv_ogm_iface_enable(st
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;
@@ -215,41 +218,59 @@ static int batadv_iv_ogm_iface_enable(st
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)
{
- ASSERT_RTNL();
+ 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;
- ASSERT_RTNL();
+ mutex_lock(&hard_iface->bat_iv.ogm_buff_mutex);
- batadv_ogm_packet = (struct batadv_ogm_packet *)ogm_buff;
+ 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;
- ASSERT_RTNL();
+ mutex_lock(&hard_iface->bat_iv.ogm_buff_mutex);
- batadv_ogm_packet = (struct batadv_ogm_packet *)ogm_buff;
+ 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 */
@@ -751,7 +772,11 @@ batadv_iv_ogm_slide_own_bcast_window(str
}
}
-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;
@@ -762,11 +787,7 @@ static void batadv_iv_ogm_schedule(struc
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;
+ 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
@@ -834,6 +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
@@ -1654,12 +1686,16 @@ static void batadv_iv_ogm_process(const
batadv_orig_node_put(orig_node);
}
-static void
-batadv_iv_send_outstanding_forw_packet(struct batadv_forw_packet *forw_packet)
+static void batadv_iv_send_outstanding_bat_ogm_packet(struct work_struct *work)
{
+ 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) {
@@ -1688,20 +1724,6 @@ 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)
{
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -17,6 +17,7 @@
#include <linux/kernel.h>
#include <linux/kref.h>
#include <linux/list.h>
+#include <linux/mutex.h>
#include <linux/netdevice.h>
#include <linux/printk.h>
#include <linux/rculist.h>
@@ -930,6 +931,7 @@ batadv_hardif_add_interface(struct net_d
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);
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -72,14 +72,17 @@ 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. rtnl protected */
+ /** @ogm_buff: buffer holding the OGM packet */
unsigned char *ogm_buff;
- /** @ogm_buff_len: length of the OGM packet buffer. rtnl protected */
+ /** @ogm_buff_len: length of the OGM packet buffer */
int ogm_buff_len;
/** @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;
};
/**
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