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Date: Thu, 17 May 2018 12:34:15 -0700
From: William Tu <u9012063@...il.com>
To: Petr Machata <petrm@...lanox.com>
Cc: Linux Kernel Network Developers <netdev@...r.kernel.org>,
David Miller <davem@...emloft.net>,
Alexey Kuznetsov <kuznet@....inr.ac.ru>,
Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
Dmitry Kozlov <xeb@...l.ru>
Subject: Re: [PATCH net 2/7] net: ip6_gre: Fix headroom request in ip6erspan_tunnel_xmit()
On Thu, May 17, 2018 at 7:36 AM, Petr Machata <petrm@...lanox.com> wrote:
> dev->needed_headroom is not primed until ip6_tnl_xmit(), so it starts
> out zero. Thus the call to skb_cow_head() fails to actually make sure
> there's enough headroom to push the ERSPAN headers to. That can lead to
> the panic cited below. (Reproducer below that).
>
> Fix by requesting either needed_headroom if already primed, or just the
> bare minimum needed for the header otherwise.
>
> [ 190.703567] kernel BUG at net/core/skbuff.c:104!
> [ 190.708384] invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
> [ 190.714007] Modules linked in: act_mirred cls_matchall ip6_gre ip6_tunnel tunnel6 gre sch_ingress vrf veth x86_pkg_temp_thermal mlx_platform nfsd e1000e leds_mlxcpld
> [ 190.728975] CPU: 1 PID: 959 Comm: kworker/1:2 Not tainted 4.17.0-rc4-net_master-custom-139 #10
> [ 190.737647] Hardware name: Mellanox Technologies Ltd. "MSN2410-CB2F"/"SA000874", BIOS 4.6.5 03/08/2016
> [ 190.747006] Workqueue: ipv6_addrconf addrconf_dad_work
> [ 190.752222] RIP: 0010:skb_panic+0xc3/0x100
> [ 190.756358] RSP: 0018:ffff8801d54072f0 EFLAGS: 00010282
> [ 190.761629] RAX: 0000000000000085 RBX: ffff8801c1a8ecc0 RCX: 0000000000000000
> [ 190.768830] RDX: 0000000000000085 RSI: dffffc0000000000 RDI: ffffed003aa80e54
> [ 190.776025] RBP: ffff8801bd1ec5a0 R08: ffffed003aabce19 R09: ffffed003aabce19
> [ 190.783226] R10: 0000000000000001 R11: ffffed003aabce18 R12: ffff8801bf695dbe
> [ 190.790418] R13: 0000000000000084 R14: 00000000000006c0 R15: ffff8801bf695dc8
> [ 190.797621] FS: 0000000000000000(0000) GS:ffff8801d5400000(0000) knlGS:0000000000000000
> [ 190.805786] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 190.811582] CR2: 000055fa929aced0 CR3: 0000000003228004 CR4: 00000000001606e0
> [ 190.818790] Call Trace:
> [ 190.821264] <IRQ>
> [ 190.823314] ? ip6erspan_tunnel_xmit+0x5e4/0x1982 [ip6_gre]
> [ 190.828940] ? ip6erspan_tunnel_xmit+0x5e4/0x1982 [ip6_gre]
> [ 190.834562] skb_push+0x78/0x90
> [ 190.837749] ip6erspan_tunnel_xmit+0x5e4/0x1982 [ip6_gre]
> [ 190.843219] ? ip6gre_tunnel_ioctl+0xd90/0xd90 [ip6_gre]
> [ 190.848577] ? debug_check_no_locks_freed+0x210/0x210
> [ 190.853679] ? debug_check_no_locks_freed+0x210/0x210
> [ 190.858783] ? print_irqtrace_events+0x120/0x120
> [ 190.863451] ? sched_clock_cpu+0x18/0x210
> [ 190.867496] ? cyc2ns_read_end+0x10/0x10
> [ 190.871474] ? skb_network_protocol+0x76/0x200
> [ 190.875977] dev_hard_start_xmit+0x137/0x770
> [ 190.880317] ? do_raw_spin_trylock+0x6d/0xa0
> [ 190.884624] sch_direct_xmit+0x2ef/0x5d0
> [ 190.888589] ? pfifo_fast_dequeue+0x3fa/0x670
> [ 190.892994] ? pfifo_fast_change_tx_queue_len+0x810/0x810
> [ 190.898455] ? __lock_is_held+0xa0/0x160
> [ 190.902422] __qdisc_run+0x39e/0xfc0
> [ 190.906041] ? _raw_spin_unlock+0x29/0x40
> [ 190.910090] ? pfifo_fast_enqueue+0x24b/0x3e0
> [ 190.914501] ? sch_direct_xmit+0x5d0/0x5d0
> [ 190.918658] ? pfifo_fast_dequeue+0x670/0x670
> [ 190.923047] ? __dev_queue_xmit+0x172/0x1770
> [ 190.927365] ? preempt_count_sub+0xf/0xd0
> [ 190.931421] __dev_queue_xmit+0x410/0x1770
> [ 190.935553] ? ___slab_alloc+0x605/0x930
> [ 190.939524] ? print_irqtrace_events+0x120/0x120
> [ 190.944186] ? memcpy+0x34/0x50
> [ 190.947364] ? netdev_pick_tx+0x1c0/0x1c0
> [ 190.951428] ? __skb_clone+0x2fd/0x3d0
> [ 190.955218] ? __copy_skb_header+0x270/0x270
> [ 190.959537] ? rcu_read_lock_sched_held+0x93/0xa0
> [ 190.964282] ? kmem_cache_alloc+0x344/0x4d0
> [ 190.968520] ? cyc2ns_read_end+0x10/0x10
> [ 190.972495] ? skb_clone+0x123/0x230
> [ 190.976112] ? skb_split+0x820/0x820
> [ 190.979747] ? tcf_mirred+0x554/0x930 [act_mirred]
> [ 190.984582] tcf_mirred+0x554/0x930 [act_mirred]
> [ 190.989252] ? tcf_mirred_act_wants_ingress.part.2+0x10/0x10 [act_mirred]
> [ 190.996109] ? __lock_acquire+0x706/0x26e0
> [ 191.000239] ? sched_clock_cpu+0x18/0x210
> [ 191.004294] tcf_action_exec+0xcf/0x2a0
> [ 191.008179] tcf_classify+0xfa/0x340
> [ 191.011794] __netif_receive_skb_core+0x8e1/0x1c60
> [ 191.016630] ? debug_check_no_locks_freed+0x210/0x210
> [ 191.021732] ? nf_ingress+0x500/0x500
> [ 191.025458] ? process_backlog+0x347/0x4b0
> [ 191.029619] ? print_irqtrace_events+0x120/0x120
> [ 191.034302] ? lock_acquire+0xd8/0x320
> [ 191.038089] ? process_backlog+0x1b6/0x4b0
> [ 191.042246] ? process_backlog+0xc2/0x4b0
> [ 191.046303] process_backlog+0xc2/0x4b0
> [ 191.050189] net_rx_action+0x5cc/0x980
> [ 191.053991] ? napi_complete_done+0x2c0/0x2c0
> [ 191.058386] ? mark_lock+0x13d/0xb40
> [ 191.062001] ? clockevents_program_event+0x6b/0x1d0
> [ 191.066922] ? print_irqtrace_events+0x120/0x120
> [ 191.071593] ? __lock_is_held+0xa0/0x160
> [ 191.075566] __do_softirq+0x1d4/0x9d2
> [ 191.079282] ? ip6_finish_output2+0x524/0x1460
> [ 191.083771] do_softirq_own_stack+0x2a/0x40
> [ 191.087994] </IRQ>
> [ 191.090130] do_softirq.part.13+0x38/0x40
> [ 191.094178] __local_bh_enable_ip+0x135/0x190
> [ 191.098591] ip6_finish_output2+0x54d/0x1460
> [ 191.102916] ? ip6_forward_finish+0x2f0/0x2f0
> [ 191.107314] ? ip6_mtu+0x3c/0x2c0
> [ 191.110674] ? ip6_finish_output+0x2f8/0x650
> [ 191.114992] ? ip6_output+0x12a/0x500
> [ 191.118696] ip6_output+0x12a/0x500
> [ 191.122223] ? ip6_route_dev_notify+0x5b0/0x5b0
> [ 191.126807] ? ip6_finish_output+0x650/0x650
> [ 191.131120] ? ip6_fragment+0x1a60/0x1a60
> [ 191.135182] ? icmp6_dst_alloc+0x26e/0x470
> [ 191.139317] mld_sendpack+0x672/0x830
> [ 191.143021] ? igmp6_mcf_seq_next+0x2f0/0x2f0
> [ 191.147429] ? __local_bh_enable_ip+0x77/0x190
> [ 191.151913] ipv6_mc_dad_complete+0x47/0x90
> [ 191.156144] addrconf_dad_completed+0x561/0x720
> [ 191.160731] ? addrconf_rs_timer+0x3a0/0x3a0
> [ 191.165036] ? mark_held_locks+0xc9/0x140
> [ 191.169095] ? __local_bh_enable_ip+0x77/0x190
> [ 191.173570] ? addrconf_dad_work+0x50d/0xa20
> [ 191.177886] ? addrconf_dad_work+0x529/0xa20
> [ 191.182194] addrconf_dad_work+0x529/0xa20
> [ 191.186342] ? addrconf_dad_completed+0x720/0x720
> [ 191.191088] ? __lock_is_held+0xa0/0x160
> [ 191.195059] ? process_one_work+0x45d/0xe20
> [ 191.199302] ? process_one_work+0x51e/0xe20
> [ 191.203531] ? rcu_read_lock_sched_held+0x93/0xa0
> [ 191.208279] process_one_work+0x51e/0xe20
> [ 191.212340] ? pwq_dec_nr_in_flight+0x200/0x200
> [ 191.216912] ? get_lock_stats+0x4b/0xf0
> [ 191.220788] ? preempt_count_sub+0xf/0xd0
> [ 191.224844] ? worker_thread+0x219/0x860
> [ 191.228823] ? do_raw_spin_trylock+0x6d/0xa0
> [ 191.233142] worker_thread+0xeb/0x860
> [ 191.236848] ? process_one_work+0xe20/0xe20
> [ 191.241095] kthread+0x206/0x300
> [ 191.244352] ? process_one_work+0xe20/0xe20
> [ 191.248587] ? kthread_stop+0x570/0x570
> [ 191.252459] ret_from_fork+0x3a/0x50
> [ 191.256082] Code: 14 3e ff 8b 4b 78 55 4d 89 f9 41 56 41 55 48 c7 c7 a0 cf db 82 41 54 44 8b 44 24 2c 48 8b 54 24 30 48 8b 74 24 20 e8 16 94 13 ff <0f> 0b 48 c7 c7 60 8e 1f 85 48 83 c4 20 e8 55 ef a6 ff 89 74 24
> [ 191.275327] RIP: skb_panic+0xc3/0x100 RSP: ffff8801d54072f0
> [ 191.281024] ---[ end trace 7ea51094e099e006 ]---
> [ 191.285724] Kernel panic - not syncing: Fatal exception in interrupt
> [ 191.292168] Kernel Offset: disabled
> [ 191.295697] ---[ end Kernel panic - not syncing: Fatal exception in interrupt ]---
>
> Reproducer:
>
> ip link add h1 type veth peer name swp1
> ip link add h3 type veth peer name swp3
>
> ip link set dev h1 up
> ip address add 192.0.2.1/28 dev h1
>
> ip link add dev vh3 type vrf table 20
> ip link set dev h3 master vh3
> ip link set dev vh3 up
> ip link set dev h3 up
>
> ip link set dev swp3 up
> ip address add dev swp3 2001:db8:2::1/64
>
> ip link set dev swp1 up
> tc qdisc add dev swp1 clsact
>
> ip link add name gt6 type ip6erspan \
> local 2001:db8:2::1 remote 2001:db8:2::2 oseq okey 123
> ip link set dev gt6 up
>
> sleep 1
>
> tc filter add dev swp1 ingress pref 1000 matchall skip_hw \
> action mirred egress mirror dev gt6
> ping -I h1 192.0.2.2
>
> Signed-off-by: Petr Machata <petrm@...lanox.com>
> ---
Acked-by: William Tu <u9012063@...il.com>
> net/ipv6/ip6_gre.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
> index 5d93c7c..53b1531 100644
> --- a/net/ipv6/ip6_gre.c
> +++ b/net/ipv6/ip6_gre.c
> @@ -911,7 +911,7 @@ static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff *skb,
> truncate = true;
> }
>
> - if (skb_cow_head(skb, dev->needed_headroom))
> + if (skb_cow_head(skb, dev->needed_headroom ?: t->hlen))
> goto tx_err;
>
> t->parms.o_flags &= ~TUNNEL_KEY;
> --
> 2.4.11
>
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