linux/net/batman-adv
Andrew Lunn 1bc4e2b000 batman-adv: Avoid endless loop in bat-on-bat netdevice check
batman-adv checks in different situation if a new device is already on top
of a different batman-adv device. This is done by getting the iflink of a
device and all its parent. It assumes that this iflink is always a parent
device in an acyclic graph. But this assumption is broken by devices like
veth which are actually a pair of two devices linked to each other. The
recursive check would therefore get veth0 when calling dev_get_iflink on
veth1. And it gets veth0 when calling dev_get_iflink with veth1.

Creating a veth pair and loading batman-adv freezes parts of the system

    ip link add veth0 type veth peer name veth1
    modprobe batman-adv

An RCU stall will be detected on the system which cannot be fixed.

    INFO: rcu_sched self-detected stall on CPU
            1: (5264 ticks this GP) idle=3e9/140000000000001/0
    softirq=144683/144686 fqs=5249
             (t=5250 jiffies g=46 c=45 q=43)
    Task dump for CPU 1:
    insmod          R  running task        0   247    245 0x00000008
     ffffffff8151f140 ffffffff8107888e ffff88000fd141c0 ffffffff8151f140
     0000000000000000 ffffffff81552df0 ffffffff8107b420 0000000000000001
     ffff88000e3fa700 ffffffff81540b00 ffffffff8107d667 0000000000000001
    Call Trace:
     <IRQ>  [<ffffffff8107888e>] ? rcu_dump_cpu_stacks+0x7e/0xd0
     [<ffffffff8107b420>] ? rcu_check_callbacks+0x3f0/0x6b0
     [<ffffffff8107d667>] ? hrtimer_run_queues+0x47/0x180
     [<ffffffff8107cf9d>] ? update_process_times+0x2d/0x50
     [<ffffffff810873fb>] ? tick_handle_periodic+0x1b/0x60
     [<ffffffff810290ae>] ? smp_trace_apic_timer_interrupt+0x5e/0x90
     [<ffffffff813bbae2>] ? apic_timer_interrupt+0x82/0x90
     <EOI>  [<ffffffff812c3fd7>] ? __dev_get_by_index+0x37/0x40
     [<ffffffffa0031f3e>] ? batadv_hard_if_event+0xee/0x3a0 [batman_adv]
     [<ffffffff812c5801>] ? register_netdevice_notifier+0x81/0x1a0
    [...]

This can be avoided by checking if two devices are each others parent and
stopping the check in this situation.

Fixes: b7eddd0b39 ("batman-adv: prevent using any virtual device created on batman-adv as hard-interface")
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
[sven@narfation.org: rewritten description, extracted fix]
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <a@unstable.cc>
2016-02-16 22:16:33 +08:00
..
bat_algo.h batman-adv: update copyright years for 2015 2015-05-29 10:13:35 +02:00
bat_iv_ogm.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-01-11 23:55:43 -05:00
bitarray.c batman-adv: Replace C99 int types with kernel type 2015-08-25 00:12:17 +02:00
bitarray.h batman-adv: Replace C99 int types with kernel type 2015-08-25 00:12:17 +02:00
bridge_loop_avoidance.c batman-adv: Avoid recursive call_rcu for batadv_bla_claim 2016-01-16 22:48:29 +08:00
bridge_loop_avoidance.h batman-adv: purge bridge loop avoidance when its disabled 2016-01-09 20:56:00 +08:00
debugfs.c batman-adv: export single hop neighbor list via debugfs 2015-12-16 00:21:42 +08:00
debugfs.h batman-adv: Remove batadv_ types forward declarations 2015-08-25 00:12:20 +02:00
distributed-arp-table.c batman-adv: Fix invalid stack access in batadv_dat_select_candidates 2015-12-07 22:40:21 +08:00
distributed-arp-table.h batman-adv: Replace C99 int types with kernel type 2015-08-25 00:12:17 +02:00
fragmentation.c batman-adv: Use chain pointer when purging fragments 2015-12-16 15:17:09 +08:00
fragmentation.h batman-adv: Add required includes to all files 2015-06-07 17:07:19 +02:00
gateway_client.c batman-adv: Only put gw_node list reference when removed 2016-02-16 17:52:25 +08:00
gateway_client.h batman-adv: remove obsolete deleted attribute for gateway node 2015-08-27 20:15:32 +02:00
gateway_common.c batman-adv: Add function to convert string to batadv throughput 2016-01-09 20:56:00 +08:00
gateway_common.h batman-adv: Remove batadv_ types forward declarations 2015-08-25 00:12:20 +02:00
hard-interface.c batman-adv: Avoid endless loop in bat-on-bat netdevice check 2016-02-16 22:16:33 +08:00
hard-interface.h batman-adv: Drop immediate batadv_hard_iface free function 2016-01-16 22:49:51 +08:00
hash.c batman-adv: Replace C99 int types with kernel type 2015-08-25 00:12:17 +02:00
hash.h batman-adv: Replace C99 int types with kernel type 2015-08-25 00:12:17 +02:00
icmp_socket.c batman-adv: Fix kerneldoc over 80 column lines 2015-08-25 00:12:18 +02:00
icmp_socket.h batman-adv: Remove batadv_ types forward declarations 2015-08-25 00:12:20 +02:00
Kconfig batman-adv: Kconfig, Add missing DEBUG_FS dependency 2015-01-07 22:17:11 +01:00
main.c batman-adv: Less checks in batadv_tvlv_unicast_send() 2016-01-09 20:56:00 +08:00
main.h batman-adv: increase BLA wait periods to 6 2016-01-09 20:56:00 +08:00
Makefile batman-adv: Makefile, Sort alphabetically 2015-05-29 10:13:36 +02:00
multicast.c batman-adv: fix lockdep splat when doing mcast_free 2016-01-13 19:26:25 +08:00
multicast.h batman-adv: Remove batadv_ types forward declarations 2015-08-25 00:12:20 +02:00
network-coding.c batman-adv: Avoid recursive call_rcu for batadv_nc_node 2016-01-16 22:48:41 +08:00
network-coding.h batman-adv: Remove batadv_ types forward declarations 2015-08-25 00:12:20 +02:00
originator.c batman-adv: Drop immediate orig_node free function 2016-01-16 22:50:00 +08:00
originator.h batman-adv: Drop immediate orig_node free function 2016-01-16 22:50:00 +08:00
packet.h batman-adv: remove leftovers of unused BATADV_PRIMARIES_FIRST_HOP flag 2016-01-09 20:56:00 +08:00
routing.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-12-17 22:08:28 -05:00
routing.h batman-adv: Remove batadv_ types forward declarations 2015-08-25 00:12:20 +02:00
send.c batman-adv: Delete unnecessary checks before the function call "kfree_skb" 2016-01-09 20:56:00 +08:00
send.h batman-adv: Remove batadv_ types forward declarations 2015-08-25 00:12:20 +02:00
soft-interface.c batman-adv: Add lower layer needed_(head|tail)room to own ones 2015-08-27 20:15:34 +02:00
soft-interface.h batman-adv: Remove batadv_ types forward declarations 2015-08-25 00:12:20 +02:00
sysfs.c batman-adv: only call post function if something changed 2016-01-09 20:56:00 +08:00
sysfs.h batman-adv: Remove batadv_ types forward declarations 2015-08-25 00:12:20 +02:00
translation-table.c batman-adv: Only put orig_node_vlan list reference when removed 2016-02-16 17:52:26 +08:00
translation-table.h batman-adv: Remove batadv_ types forward declarations 2015-08-25 00:12:20 +02:00
types.h batman-adv: Add kerneldoc for batadv_neigh_node::refcount 2016-01-09 20:56:00 +08:00