Date:	Tue, 21 May 2013 11:01:32 +0300
From:	Timo Teras <timo.teras@....fi>
To:	Pravin Shelar <pshelar@...ira.com>
Cc:	netdev@...r.kernel.org
Subject: Re: GRE+XFRM+GSO crashes

On Mon, 20 May 2013 10:58:03 -0700
Pravin Shelar <pshelar@...ira.com> wrote:

> On Sun, May 19, 2013 at 11:41 PM, Timo Teras <timo.teras@....fi>
> wrote:
> > Since upgrade from 3.8 to 3.9 I've started getting the below
> > mentioned BUG crashes. One of the few relevant changes seems to be
> > GSO support in GRE driver.
> >
> > Turning off SG (and GSO) seems to make these crashes disappear.
> >
> > The basic setup is:
> > - gre1 is an NBMA tunnel (no explicit destination, nor bound
> >   target interface; opennhrp daemon creates neigh mappings)
> > - IPsec policy to encrypt all GRE traffic in transport mode
> > - VIA Padlock hardware for AES acceleration
> > - GRE traffic goes to r8169 NIC; rx on, gro on, tx off, sg off, gso
> > off
> >
> > Incidentally, when I tried exact same setup ran as virtualized, I
> > was unable to reproduce this crash. I suspect it depends on the
> > target NIC acceleration capabilities.
> >
> I do not have access to this hardware, can you tell me what are target
> device capabilities?

The physical hardware from which the OOPS is from:

r8169 0000:00:09.0 eth0: RTL8169sc/8110sc at 0xf801c000, 00:30:18:a8:14:ac, XID 18000000 IRQ 18
r8169 0000:00:09.0 eth0: jumbo features [frames: 7152 bytes, tx checksumming: ok]

(defaults after boot)
Offload parameters for eth0:
rx-checksumming: on
tx-checksumming: off
scatter-gather: off
tcp-segmentation-offload: off
udp-fragmentation-offload: off
generic-segmentation-offload: off
generic-receive-offload: on
large-receive-offload: off
rx-vlan-offload: on
tx-vlan-offload: on
ntuple-filters: off
receive-hashing: off

When running virtualized in which I was unable to reproduce this OOPS:

e1000 0000:00:03.0 eth0: (PCI:33MHz:32-bit) 52:54:00:12:34:56
e1000 0000:00:03.0 eth0: Intel(R) PRO/1000 Network Connection

Offload parameters for eth0:
rx-checksumming: off
tx-checksumming: on
scatter-gather: on
tcp-segmentation-offload: on
udp-fragmentation-offload: off
generic-segmentation-offload: on
generic-receive-offload: on
large-receive-offload: off
rx-vlan-offload: on
tx-vlan-offload: on
ntuple-filters: off
receive-hashing: off

> 
> Thanks,
> Pravin.
> > This is from vanilla 3.9.2 kernel:
> >  BUG: unable to handle kernel NULL pointer dereference at 00000010
> >  IP: [<c123e5b8>] xfrm_output_resume+0x63/0x2a4
> >  *pde = 00000000
> >  Oops: 0000 [#1] SMP
> >  Modules linked in: sha1_generic authenc esp4 xfrm4_mode_transport
> >  deflate zlib_deflate ctr twofish_i586 twofish_generic
> > twofish_common camellia_generic serpent_sse2_i586 xts lrw gf128mul
> > glue_helper ablk_helper cryptd serpent_generic blowfish_generic
> > blowfish_common cast5_generic cast_common des_generic cbc xcbc
> > rmd160 sha512_generic hmac crypto_null af_key xfrm_algo ip_gre
> > ipt_REJECT iptable_filter ipt_MASQUERADE xt_nat iptable_nat
> > nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat ip_tables
> > ip6t_REJECT xt_LOG xt_limit xt_recent xt_policy xt_tcpudp
> > nf_conntrack_ipv6 nf_defrag_ipv6 xt_state nf_conntrack xt_multiport
> > ip6table_filter ip6_tables x_tables ipv6 af_packet padlock_sha
> > padlock_aes via_cputemp hwmon hwmon_vid serio_raw psmouse pcspkr
> > shpchp pci_hotplug i2c_viapro i2c_core via_rhine snd_via82xx
> > snd_ac97_codec snd_pcm snd_timer ac97_bus snd_page_alloc
> > snd_mpu401_uart snd_rawmidi snd_seq_device snd soundcore
> > firewire_ohci firewire_core crc_itu_t via_agp agpgart r8169
> > firmware_class mii evdev fan parport_pc parport thermal button
> > acpi_cpufreq freq_table mperf processor nls_utf8 nls_cp437 vfat fat
> > sata_via ehci_pci ehci_hcd uhci_hcd ata_generic pata_via pata_acpi
> > libata usb_storage usbcore usb_common sd_mod scsi_mod squashfs loop
> > Pid: 1794, comm: opennhrp Not tainted 3.9.2
> > #2-Alpine    /CN700-8237 EIP: 0060:[<c123e5b8>] EFLAGS: 00010246
> > CPU: 0 EIP is at xfrm_output_resume+0x63/0x2a4 EAX: 00000000 EBX:
> > f0572500 ECX: f5ffc8b8 EDX: 00000064 ESI: f0496400 EDI: 00000000
> > EBP: f0499bf8 ESP: f0499be8 DS: 007b ES: 007b FS: 00d8 GS: 0033 SS:
> > 0068 CR0: 80050033 CR2: 00000010 CR3: 3104c000 CR4: 00000690
> >  DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
> >  DR6: ffff0ff0 DR7: 00000400
> >  Process opennhrp (pid: 1794, ti=f0498000 task=f670eff0
> > task.ti=f0498000) Stack:
> >   f0496420 f0572500 c1236810 f0572528 f0499c00 c123e806 f0499c14
> > c123e89b f0572500 c1236810 f0572528 f0499c1c c1236837 f0499c2c
> > c1236865 f0572500 0000003c f0499c38 c12016e7 f0572500 f0499cb0
> > f84175fb f0572a00 f04bb400 Call Trace:
> >   [<c1236810>] ? xfrm4_extract_output+0x8c/0x8c
> >   [<c123e806>] xfrm_output2+0xd/0xf
> >   [<c123e89b>] xfrm_output+0x93/0xa0
> >   [<c1236810>] ? xfrm4_extract_output+0x8c/0x8c
> >   [<c1236837>] xfrm4_output_finish+0x27/0x29
> >   [<c1236865>] xfrm4_output+0x2c/0x63
> >   [<c12016e7>] ip_local_out+0x1b/0x1e
> >   [<f84175fb>] ipgre_tunnel_xmit+0x80a/0x892 [ip_gre]
> >   [<c11ddff1>] dev_hard_start_xmit+0x27d/0x37c
> >   [<c11de379>] dev_queue_xmit+0x289/0x31a
> >   [<f8332308>] packet_sendmsg+0x933/0x9d0 [af_packet]
> >   [<c1040200>] ? ttwu_do_wakeup+0xe/0xa8
> >   [<f8416874>] ? ipgre_header_parse+0x15/0x15 [ip_gre]
> >   [<c11cd5a9>] sock_sendmsg+0x79/0x94
> >   [<c10b33d4>] ? __pollwait+0xa4/0xa4
> >   [<c11cd7e3>] __sys_sendmsg+0x16e/0x1f3
> >   [<c10367c5>] ? free_pid+0x99/0x9f
> >   [<c106b92a>] ? call_rcu_sched+0xf/0x12
> >   [<c1026e15>] ? release_task+0x36d/0x37d
> >   [<c10390e8>] ? remove_wait_queue+0x31/0x36
> >   [<c1027a1d>] ? do_wait+0x1a8/0x1b5
> >   [<c11cef10>] sys_sendmsg+0x2b/0x46
> >   [<c11cf394>] sys_socketcall+0x145/0x19f
> >   [<c1257888>] syscall_call+0x7/0xb
> >  Code: ff 8b 43 74 c7 43 70 00 00 00 00 85 c0 74 0f 3e ff 08 0f 94
> > c2 84 d2 74 05 e8 35 17 e6 ff 8b 43 48 c7 43 74 00 00 00 00 83 e0
> > fe <8b> 50 10 89 d8 ff 52 34 83 f8 01 89 c7 0f 85 24 02 00 00 8b 53
> > EIP: [<c123e5b8>] xfrm_output_resume+0x63/0x2a4 SS:ESP
> > 0068:f0499be8 CR2: 0000000000000010 ---[ end trace ac96c6b6b1a4992f
> > ]--- Kernel panic - not syncing: Fatal exception in interrupt
> >
> >
> > Based on the disassembly, it seems the crash happens in
> > net/xfrm/xfrm_output.c:
> >
> > int xfrm_output_resume(struct sk_buff *skb, int err)
> > {
> >         while (likely((err = xfrm_output_one(skb, err)) == 0)) {
> >                 nf_reset(skb);
> >
> >                 err = skb_dst(skb)->ops->local_out(skb);
> >                       ^^^^^^^^^^^^ is NULL
> >                 if (unlikely(err != 1))
> >                         goto out;
> >
> >                 if (!skb_dst(skb)->xfrm)
> >                         return dst_output(skb);

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