Re: ip_rcv_finish() NULL pointer and possibly related Oopses
From: Chuck Ebbert <hidden>
Date: 2015-08-26 11:50:07
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On Wed, 26 Aug 2015 08:46:59 +0000 Shaun Crampton [off-list ref] wrote:
Testing our app at scale on Google¹s GCE, running ~1000 CoreOS hosts: over approximately 1 hour, I see about 1 in 50 hosts hit one of the Oopses below and then reboot (I¹m not sure if the different oopses are related to each other). The app is Project Calico, which is a datacenter networking fabric. calico-felix, the process named below, is our per-host agent. The per-host agent is responsible for reading the network information from a central server and applying "ip route² and "iptables" updates to the kernel. We¹re running on CoreOS, with about 100 docker containers/veths pairs running on each host. calico-felix is running inside one of those containers. We also run the BIRD BGP stack to redistribute routes around the datacenter. The errors happen more frequently while Calico is under load. I¹m not sure where to go from here. I can reproduce these issues easily at that scale but I haven¹t managed to boil it down to a small-scale repro scenario for further investigation (yet).
What in the world is going on with those call traces? E.g.:
[ 4513.712008] <IRQ> [ 4513.712008] [<ffffffff81486751>] ? ip_rcv_finish+0x81/0x360 [ 4513.712008] [<ffffffff814870e4>] ip_rcv+0x2a4/0x400 [ 4513.712008] [<ffffffff814866d0>] ? inet_del_offload+0x40/0x40 [ 4513.712008] [<ffffffff814491b3>] __netif_receive_skb_core+0x6c3/0x9a0 [ 4513.712008] [<ffffffff8143b667>] ? build_skb+0x17/0x90 [ 4513.712008] [<ffffffff814494a8>] __netif_receive_skb+0x18/0x60 [ 4513.712008] [<ffffffff81449523>] netif_receive_skb_internal+0x33/0xa0 [ 4513.712008] [<ffffffff814495ac>] netif_receive_skb_sk+0x1c/0x70 [ 4513.712008] [<ffffffffa00f772b>] 0xffffffffa00f772b [ 4513.712008] [<ffffffff814491b3>] ? __netif_receive_skb_core+0x6c3/0x9a0 [ 4513.712008] [<ffffffffa00f7d81>] 0xffffffffa00f7d81 [ 4513.712008] [<ffffffff81449979>] net_rx_action+0x159/0x340 [ 4513.712008] [<ffffffff810715f4>] __do_softirq+0xf4/0x290 [ 4513.712008] [<ffffffff810719fd>] irq_exit+0xad/0xc0 [ 4513.712008] [<ffffffff815528ba>] do_IRQ+0x5a/0xf0 [ 4513.712008] [<ffffffff815507ae>] common_interrupt+0x6e/0x6e [ 4513.712008] <EOI>
There are two functions in the call trace that the kernel knows nothing about. How did they get in there? And there is really executable code in there, as can be seen from a later trace:
[ 4123.003006] <IRQ> [ 4123.003006] [<ffffffff8147d477>] nf_iterate+0x57/0x80 [ 4123.003006] [<ffffffff8147d537>] nf_hook_slow+0x97/0x100 [ 4123.003006] [<ffffffff81486e32>] ip_local_deliver+0x92/0xa0 [ 4123.003006] [<ffffffff81486a30>] ? ip_rcv_finish+0x360/0x360 [ 4123.003006] [<ffffffff81486751>] ip_rcv_finish+0x81/0x360 [ 4123.003006] [<ffffffff814870e4>] ip_rcv+0x2a4/0x400 [ 4123.003006] [<ffffffff814866d0>] ? inet_del_offload+0x40/0x40 [ 4123.003006] [<ffffffff814491b3>] __netif_receive_skb_core+0x6c3/0x9a0 [ 4123.003006] [<ffffffff8143b667>] ? build_skb+0x17/0x90 [ 4123.003006] [<ffffffff814494a8>] __netif_receive_skb+0x18/0x60 [ 4123.003006] [<ffffffff81449523>] netif_receive_skb_internal+0x33/0xa0 [ 4123.003006] [<ffffffff814495ac>] netif_receive_skb_sk+0x1c/0x70 [ 4123.003006] [<ffffffffa00d472b>] 0xffffffffa00d472b [ 4123.003006] [<ffffffffa00d4d81>] 0xffffffffa00d4d81 [ 4123.003006] [<ffffffff81449979>] net_rx_action+0x159/0x340 [ 4123.003006] [<ffffffff810715f4>] __do_softirq+0xf4/0x290 [ 4123.003006] [<ffffffff810719fd>] irq_exit+0xad/0xc0 [ 4123.003006] [<ffffffff815528ba>] do_IRQ+0x5a/0xf0 [ 4123.003006] [<ffffffff815507ae>] common_interrupt+0x6e/0x6e [ 4123.003006] <EOI> [ 4123.003006] [<ffffffff81483a3d>] ? __ip_route_output_key+0x31d/0x860 [ 4123.003006] [<ffffffff814e2e95>] ? xfrm_lookup_route+0x5/0x70 [ 4123.003006] [<ffffffff81484224>] ? ip_route_output_flow+0x54/0x60 [ 4123.003006] [<ffffffff8148ca6a>] ip_queue_xmit+0x36a/0x3d0 [ 4123.003006] [<ffffffff814a4799>] tcp_transmit_skb+0x4b9/0x990 [ 4123.003006] [<ffffffff814a4d85>] tcp_write_xmit+0x115/0xe90 [ 4123.003006] [<ffffffff814a5d72>] __tcp_push_pending_frames+0x32/0xd0 [ 4123.003006] [<ffffffff8149443f>] tcp_push+0xef/0x120 [ 4123.003006] [<ffffffff81497cb5>] tcp_sendmsg+0xc5/0xb20 [ 4123.003006] [<ffffffff810d74c9>] ? lock_hrtimer_base.isra.22+0x29/0x50 [ 4123.003006] [<ffffffff814c2d04>] inet_sendmsg+0x64/0xa0 [ 4123.003006] [<ffffffff811e94b5>] ? __fget_light+0x25/0x70 [ 4123.003006] [<ffffffff8142d74d>] sock_sendmsg+0x3d/0x50 [ 4123.003006] [<ffffffff8142dc12>] SYSC_sendto+0x102/0x1a0 [ 4123.003006] [<ffffffff8110f864>] ? __audit_syscall_entry+0xb4/0x110 [ 4123.003006] [<ffffffff810224fc>] ? do_audit_syscall_entry+0x6c/0x70 [ 4123.003006] [<ffffffff81023cf3>] ? syscall_trace_enter_phase1+0x103/0x160 [ 4123.003006] [<ffffffff8142e75e>] SyS_sendto+0xe/0x10 [ 4123.003006] [<ffffffff8154fc6e>] system_call_fastpath+0x12/0x71 [ 4123.003006] Code: <48> 8b 88 40 03 00 00 e8 1d dd dd ff 5d c3 0f 1f 00 41 83 b9 80 00 [ 4123.003006] RIP [<ffffffffa0233027>] 0xffffffffa0233027 [ 4123.003006] RSP <ffff88021fc03b58>
Presumably the same two functions as before (loaded at a different base address but same offsets, 0xd81 and 0x72b). And then nf_iterate call into another unknown function, and there really is code there and it's consistent with the oops. And the kernel thinks it's outside of any normal text section, so it does not try to dump any code from before the instruction pointer. 0: 48 8b 88 40 03 00 00 mov 0x340(%rax),%rcx 7: e8 1d dd dd ff callq 0xffffffffffdddd29 c: 5d pop %rbp d: c3 retq Did you write your own module loader or something?