batman-adv: Avoid duplicate neigh_node additions
Two parallel calls to batadv_neigh_node_new() might race for creating
and adding the same neig_node. Fix this by including the check for any
already existing, identical neigh_node within the spin-lock.
This fixes splats like the following:
[ 739.535069] ------------[ cut here ]------------
[ 739.535079] WARNING: CPU: 0 PID: 0 at /usr/src/batman-adv/git/batman-adv/net/batman-adv/bat_iv_ogm.c:1004 batadv_iv_ogm_process_per_outif+0xe3f/0xe60 [batman_adv]()
[ 739.535092] too many matching neigh_nodes
[ 739.535094] Modules linked in: dm_mod tun ip6table_filter ip6table_mangle ip6table_nat nf_nat_ipv6 ip6_tables xt_nat iptable_nat nf_nat_ipv4 nf_nat xt_TCPMSS xt_mark iptable_mangle xt_tcpudp xt_conntrack iptable_filter ip_tables x_tables ip_gre ip_tunnel gre bridge stp llc thermal_sys kvm_intel kvm crct10dif_pclmul crc32_pclmul sha256_ssse3 sha256_generic hmac drbg ansi_cprng aesni_intel aes_x86_64 lrw gf128mul glue_helper ablk_helper cryptd evdev pcspkr ip6_gre ip6_tunnel tunnel6 batman_adv(O) libcrc32c nf_conntrack_ipv6 nf_defrag_ipv6 nf_conntrack_ipv4 nf_defrag_ipv4 nf_conntrack autofs4 ext4 crc16 mbcache jbd2 xen_netfront xen_blkfront crc32c_intel
[ 739.535177] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G W O 4.2.0-0.bpo.1-amd64 #1 Debian 4.2.6-3~bpo8+2
[ 739.535186] 0000000000000000 ffffffffa013b050 ffffffff81554521 ffff88007d003c18
[ 739.535201] ffffffff8106fa01 0000000000000000 ffff8800047a087a ffff880079c3a000
[ 739.735602] ffff88007b82bf40 ffff88007bc2d1c0 ffffffff8106fa7a ffffffffa013aa8e
[ 739.735624] Call Trace:
[ 739.735639] <IRQ> [<ffffffff81554521>] ? dump_stack+0x40/0x50
[ 739.735677] [<ffffffff8106fa01>] ? warn_slowpath_common+0x81/0xb0
[ 739.735692] [<ffffffff8106fa7a>] ? warn_slowpath_fmt+0x4a/0x50
[ 739.735715] [<ffffffffa012448f>] ? batadv_iv_ogm_process_per_outif+0xe3f/0xe60 [batman_adv]
[ 739.735740] [<ffffffffa0124813>] ? batadv_iv_ogm_receive+0x363/0x380 [batman_adv]
[ 739.735762] [<ffffffffa0124813>] ? batadv_iv_ogm_receive+0x363/0x380 [batman_adv]
[ 739.735783] [<ffffffff810b0841>] ? __raw_callee_save___pv_queued_spin_unlock+0x11/0x20
[ 739.735804] [<ffffffffa012cb39>] ? batadv_batman_skb_recv+0xc9/0x110 [batman_adv]
[ 739.735825] [<ffffffff81464891>] ? __netif_receive_skb_core+0x841/0x9a0
[ 739.735838] [<ffffffff810b0841>] ? __raw_callee_save___pv_queued_spin_unlock+0x11/0x20
[ 739.735853] [<ffffffff81465681>] ? process_backlog+0xa1/0x140
[ 739.735864] [<ffffffff81464f1a>] ? net_rx_action+0x20a/0x320
[ 739.735878] [<ffffffff81073aa7>] ? __do_softirq+0x107/0x270
[ 739.735891] [<ffffffff81073d82>] ? irq_exit+0x92/0xa0
[ 739.735905] [<ffffffff8137e0d1>] ? xen_evtchn_do_upcall+0x31/0x40
[ 739.735924] [<ffffffff8155b8fe>] ? xen_do_hypervisor_callback+0x1e/0x40
[ 739.735939] <EOI> [<ffffffff810013aa>] ? xen_hypercall_sched_op+0xa/0x20
[ 739.735965] [<ffffffff810013aa>] ? xen_hypercall_sched_op+0xa/0x20
[ 739.735979] [<ffffffff8100a39c>] ? xen_safe_halt+0xc/0x20
[ 739.735991] [<ffffffff8101da6c>] ? default_idle+0x1c/0xa0
[ 739.736004] [<ffffffff810abf6b>] ? cpu_startup_entry+0x2eb/0x350
[ 739.736019] [<ffffffff81b2af5e>] ? start_kernel+0x480/0x48b
[ 739.736032] [<ffffffff81b2d116>] ? xen_start_kernel+0x507/0x511
[ 739.736048] ---[ end trace c106bb901244bc8c ]---
Fixes: f987ed6ebd99 ("batman-adv: protect neighbor list with rcu locks")
Reported-by: Martin Weinelt <martin@darmstadt.freifunk.net>
Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <a@unstable.cc>
diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c
index 1ff4ee4..7f51bc2 100644
--- a/net/batman-adv/originator.c
+++ b/net/batman-adv/originator.c
@@ -619,6 +619,8 @@
struct batadv_neigh_node *neigh_node;
struct batadv_hardif_neigh_node *hardif_neigh = NULL;
+ spin_lock_bh(&orig_node->neigh_list_lock);
+
neigh_node = batadv_neigh_node_get(orig_node, hard_iface, neigh_addr);
if (neigh_node)
goto out;
@@ -650,15 +652,15 @@
kref_init(&neigh_node->refcount);
kref_get(&neigh_node->refcount);
- spin_lock_bh(&orig_node->neigh_list_lock);
hlist_add_head_rcu(&neigh_node->list, &orig_node->neigh_list);
- spin_unlock_bh(&orig_node->neigh_list_lock);
batadv_dbg(BATADV_DBG_BATMAN, orig_node->bat_priv,
"Creating new neighbor %pM for orig_node %pM on interface %s\n",
neigh_addr, orig_node->orig, hard_iface->net_dev->name);
out:
+ spin_unlock_bh(&orig_node->neigh_list_lock);
+
if (hardif_neigh)
batadv_hardif_neigh_put(hardif_neigh);
return neigh_node;