Re: [B.A.T.M.A.N.] kernel BUG at net/core/skbuff.c:100

Philipp Psurek
2014-11-24T21:15:21Z

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Hello again

Now it becomes a running gag, ;-) but I really try to provide you with
some information about this bug.

Now we needn't to wait until next Monday. The bug appears also with NC
and MM disabled.

Do you need this back-traces? Can you see something inside besides magic
numbers? Somehow it should be possible to extract the bogus packages
from vmcore with crash or some other utility to reproduce the bug.

Please tell me what to do.

Best regards

Philipp

________________________
Freifunk Rheinland e. V.
– Funkzelle Wuppertal –

SYSTEM MAP: /boot/System.map
DEBUG KERNEL: /usr/src/linux-3.16.7-gentoo/vmlinux (3.16.7-gentoo)
DUMPFILE: vmcore_20141124212740
CPUS: 1
DATE: Mon Nov 24 21:01:11 2014
UPTIME: 08:13:54
LOAD AVERAGE: 0.27, 0.28, 0.23
TASKS: 125
NODENAME: wolke
RELEASE: 3.16.7-gentoo
VERSION: #1 SMP Mon Nov 17 03:44:22 CET 2014
MACHINE: x86_64 (2593 Mhz)
MEMORY: 511.6 MB
PANIC: "kernel BUG at net/core/skbuff.c:100!"
PID: 1993
COMMAND: "fastd"
TASK: ffff88001f3369c0 [THREAD_INFO: ffff880019ff0000]
CPU: 0
STATE: TASK_RUNNING (PANIC)

crash> bt
PID: 1993 TASK: ffff88001f3369c0 CPU: 0 COMMAND: "fastd"
#0 [ffff88001fc03980] machine_kexec at ffffffff8103a34e
#1 [ffff88001fc039e0] crash_kexec at ffffffff810be503
#2 [ffff88001fc03ab0] oops_end at ffffffff81005fc8
#3 [ffff88001fc03ae0] die at ffffffff81006463
#4 [ffff88001fc03b10] do_trap at ffffffff81002e12
#5 [ffff88001fc03b70] do_error_trap at ffffffff8100316d
#6 [ffff88001fc03c30] do_invalid_op at ffffffff8100394b
#7 [ffff88001fc03c40] invalid_op at ffffffff817f385e
[exception RIP: skb_panic+94]
RIP: ffffffff817eb99d RSP: ffff88001fc03cf8 RFLAGS: 00010296
RAX: 000000000000008b RBX: ffff88000f9a4e80 RCX: 0000000000000092
RDX: 000000000000001f RSI: 0000000000000046 RDI: 0000000000000246
RBP: ffff88001fc03d18 R8: 0000000000000000 R9: 0000000000000000
R10: 00000000000001b0 R11: 0000000000000006 R12: 0000000000000564
R13: ffff88001fc03da0 R14: ffff880019f69000 R15: ffff880007130062
ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018
#8 [ffff88001fc03d20] skb_put at ffffffff81611bb1
#9 [ffff88001fc03d30] batadv_frag_skb_buffer at ffffffffa001be12 [batman_adv]
#10 [ffff88001fc03d90] batadv_recv_frag_packet at ffffffffa0026273 [batman_adv]
#11 [ffff88001fc03dd0] batadv_batman_skb_recv at ffffffffa001fef5 [batman_adv]
#12 [ffff88001fc03e10] __netif_receive_skb_core at ffffffff81621962
#13 [ffff88001fc03e80] __netif_receive_skb at ffffffff81621e91
#14 [ffff88001fc03ea0] process_backlog at ffffffff81621f7e
#15 [ffff88001fc03ef0] net_rx_action at ffffffff81622731
#16 [ffff88001fc03f50] __do_softirq at ffffffff81053ef8
#17 [ffff88001fc03fb0] do_softirq_own_stack at ffffffff817f3a5c
--- <IRQ stack> ---
#18 [ffff880019ff3d10] do_softirq_own_stack at ffffffff817f3a5c
[exception RIP: tun_get_user+1056]
RIP: ffffffffa00098f0 RSP: 0000000000000001 RFLAGS: 7fff00000586
RAX: ffffffff816210b4 RBX: ffff880019ff3d58 RCX: ffff880017710780
RDX: 0000000000000000 RSI: ffff880017710780 RDI: 0000000000000586
RBP: ffffffff81620de4 R8: ffff880019ff3d88 R9: ffff880017710780
R10: ffff880017710780 R11: ffffffff81054135 R12: ffff880019ff3d58
R13: 0000000000000586 R14: ffff880019f69e00 R15: 0000000000000000
ORIG_RAX: ffff880019ff3e38 CS: 7ffffd27ec80 SS: 0000
bt: WARNING: possibly bogus exception frame
#19 [ffff880019ff3e40] tun_chr_aio_write at ffffffffa0009e0b [tun]
#20 [ffff880019ff3e70] do_sync_write at ffffffff8115c665
#21 [ffff880019ff3f00] vfs_write at ffffffff8115d38a
#22 [ffff880019ff3f40] sys_write at ffffffff8115d89a
#23 [ffff880019ff3f80] system_call_fastpath at ffffffff817f1f29
RIP: 00007f24ad2c037d RSP: 00007ffffd27ea18 RFLAGS: 00010246
RAX: 0000000000000001 RBX: ffffffff817f1f29 RCX: 0000000000000003
RDX: 0000000000000586 RSI: 00000000008c9ff0 RDI: 0000000000000009
RBP: 0000000000000586 R8: 00007f24ad2a9400 R9: 00007ffffd27e3c8
R10: 00007ffffd27eb0f R11: 0000000000000293 R12: 00000000008c99f8
R13: 0000000000000001 R14: 00000000008c9fe0 R15: 00000000008b86e0
ORIG_RAX: 0000000000000001 CS: 0033 SS: 002b
crash> log
[ … ]
[ 46.421671] Adding 1571836k swap on /dev/vda2. Priority:-1 extents:1 across:1571836k
[ 61.663553] crond (1525) used greatest stack depth: 11944 bytes left
[ 94.611478] device eth0 entered promiscuous mode
[ 95.050264] random: nonblocking pool is initialized
[ 97.767718] sshd (1896) used greatest stack depth: 11848 bytes left
[ 155.371394] tun: Universal TUN/TAP device driver, 1.6
[ 155.371402] tun: (C) 1999-2004 Max Krasnyansky <maxk@qualcomm.com>
[ 160.085539] batman_adv: B.A.T.M.A.N. advanced 2014.3.0 (compatibility version 15) loaded
[ 161.520244] batman_adv: bat0: Adding interface: fastd0
[ 161.520248] batman_adv: bat0: The MTU of interface fastd0 is too small (1426) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1560 would solve the problem.
[ 161.520251] batman_adv: bat0: Interface activated: fastd0
[ 161.521317] batman_adv: bat0: orig_interval: Changing from: 1000 to: 5000
[ 161.522871] batman_adv: bat0: bridge_loop_avoidance: Changing from: disabled to: enabled
[ 161.523606] batman_adv: bat0: Changing gw mode from: off to: client
[ 163.534130] ipip: IPv4 over IPv4 tunneling driver
[ 240.083770] batman_adv: bat0: Changing gw mode from: client to: server
[ 240.083793] batman_adv: bat0: Changing gateway bandwidth from: '10.0/2.0 MBit' to: '100.0/100.0 MBit'
[ 240.089611] batman_adv: bat0: network_coding: Changing from: enabled to: disabled
[ 632.809027] nf_conntrack: automatic helper assignment is deprecated and it will be removed soon. Use the iptables CT target to attach helpers instead.
[ 878.974740] batman_adv: bat0: multicast_mode: Changing from: enabled to: disabled
[ 7311.887428] named (9682) used greatest stack depth: 11720 bytes left
[25080.989287] UDP: bad checksum. From _._._._:26085 to _._._._:25901 ulen 76
[25081.134015] UDP: bad checksum. From _._._._:26085 to _._._._:25901 ulen 75
[25125.828688] UDP: bad checksum. From _._._._:26085 to _._._._:31502 ulen 79
[25225.232627] UDP: bad checksum. From _._._._:26085 to _._._._:25901 ulen 75
[25323.805796] UDP: bad checksum. From _._._._:26085 to _._._._:25901 ulen 76
[25355.026288] UDP: bad checksum. From _._._._:26085 to _._._._:25901 ulen 76
[29634.048268] skbuff: skb_over_panic: text:ffffffffa001be12 len:1459 put:1380 head:ffff8800049c4000 data:ffff8800049c4062 tail:0x615 end:0x2c0 dev:fastd0
[29634.048580] ------------[ cut here ]------------
[29634.048686] kernel BUG at net/core/skbuff.c:100!
[29634.048781] invalid opcode: 0000 [#1] SMP
[29634.048881] Modules linked in: xt_nat iptable_nat nf_nat_ipv4 nf_nat ipip batman_adv libcrc32c tun crc32c_intel
[29634.049175] CPU: 0 PID: 1993 Comm: fastd Not tainted 3.16.7-gentoo #1
[29634.049198] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2007
[29634.049198] task: ffff88001f3369c0 ti: ffff880019ff0000 task.ti: ffff880019ff0000
[29634.049198] RIP: 0010:[<ffffffff817eb99d>] [<ffffffff817eb99d>] skb_panic+0x5e/0x60
[29634.049198] RSP: 0018:ffff88001fc03cf8 EFLAGS: 00010296
[29634.049198] RAX: 000000000000008b RBX: ffff88000f9a4e80 RCX: 0000000000000092
[29634.049198] RDX: 000000000000001f RSI: 0000000000000046 RDI: 0000000000000246
[29634.049198] RBP: ffff88001fc03d18 R08: 0000000000000000 R09: 0000000000000000
[29634.049198] R10: 00000000000001b0 R11: 0000000000000006 R12: 0000000000000564
[29634.049198] R13: ffff88001fc03da0 R14: ffff880019f69000 R15: ffff880007130062
[29634.049198] FS: 00007f24adf6c700(0000) GS:ffff88001fc00000(0000) knlGS:0000000000000000
[29634.049198] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[29634.049198] CR2: 00007f9b1be31000 CR3: 00000000175ff000 CR4: 00000000000006f0
[29634.049198] Stack:
[29634.049198] ffff8800049c4062 0000000000000615 00000000000002c0 ffff880017710000
[29634.049198] ffff88001fc03d28 ffffffff81611bb1 ffff88001fc03d88 ffffffffa001be12
[29634.049198] ffff8800176f21c8 ffff88000713004e ffff88001fc03d78 ffff88000f9a4e80
[29634.049198] Call Trace:
[29634.049198] <IRQ>
[29634.049198]
[29634.049198] [<ffffffff81611bb1>] skb_put+0x41/0x50
[29634.049198] [<ffffffffa001be12>] batadv_frag_skb_buffer+0x272/0x470 [batman_adv]
[29634.049198] [<ffffffffa0026273>] batadv_recv_frag_packet+0x183/0x200 [batman_adv]
[29634.049198] [<ffffffffa001fef5>] batadv_batman_skb_recv+0xd5/0x110 [batman_adv]
[29634.049198] [<ffffffff81621962>] __netif_receive_skb_core+0x222/0x730
[29634.049198] [<ffffffff81621e91>] __netif_receive_skb+0x21/0x70
[29634.049198] [<ffffffff81621f7e>] process_backlog+0x9e/0x170
[29634.049198] [<ffffffff81622731>] net_rx_action+0x141/0x240
[29634.049198] [<ffffffff81053ef8>] __do_softirq+0xe8/0x280
[29634.049198] [<ffffffff817f3a5c>] do_softirq_own_stack+0x1c/0x30
[29634.049198] <EOI>
[29634.049198]
[29634.049198] [<ffffffff81054135>] do_softirq+0x55/0x60
[29634.049198] [<ffffffff816210b4>] netif_rx_ni+0x34/0x70
[29634.049198] [<ffffffffa00098f0>] tun_get_user+0x420/0x840 [tun]
[29634.049198] [<ffffffffa0009e0b>] tun_chr_aio_write+0x7b/0xa0 [tun]
[29634.049198] [<ffffffff8115c665>] do_sync_write+0x55/0x90
[29634.049198] [<ffffffff8115d38a>] vfs_write+0xba/0x1f0
[29634.049198] [<ffffffff8115d89a>] SyS_write+0x4a/0xa0
[29634.049198] [<ffffffff817f1f29>] system_call_fastpath+0x16/0x1b
[29634.049198] Code: 00 00 48 89 44 24 10 8b 87 c0 00 00 00 48 89 44 24 08 48 8b 87 d0 00 00 00 48 c7 c7 30 67 a3 81 48 89 04 24 31 c0 e8 0d 8b ff ff <0f> 0b 55 48 89 f8 48 8b 57 30 48 89 e5 48 8b 0f 5d 80 e5 80 48
[29634.049198] RIP [<ffffffff817eb99d>] skb_panic+0x5e/0x60
[29634.049198] RSP <ffff88001fc03cf8>