Re: [PATCH stable 4.1] openvswitch: gre: filter gre packets

On 8 January 2017 at 06:14, Pravin B Shelar [off-list ref] wrote:

OVS can only process L2 packets. But OVS GRE receive handler
can accept IP-GRE packets. When such packet is processed by
OVS datapath it can trigger following assert failure due
to insufficient linear data in skb. Following patch filters
received packets to avoid this issue.

[68240.441681] ------------[ cut here ]------------
[68240.496918] kernel BUG at /build/linux-lts-trusty-D60X6T/linux-lts-trusty-3.13.0/include/linux/skbuff.h:1486!
[68240.615520] invalid opcode: 0000 [#1] SMP
[68241.953939] RIP: [<ffffffffa052b4fe>] __skb_pull.part.7+0x4/0x6 [openvswitch]
[68243.099945] Call Trace:
[68243.129188]  <IRQ>
[68243.152204]  [<ffffffffa0524e64>] ovs_flow_extract+0x664/0x720 [openvswitch]
[68243.314912]  [<ffffffffa0523a80>] ovs_dp_process_received_packet+0x60/0x130 [openvswitch]
[68243.481559]  [<ffffffffa0529e3a>] ovs_vport_receive+0x2a/0x30 [openvswitch]
[68243.564884]  [<ffffffffa052b374>] gre_rcv+0xa4/0xb8 [openvswitch]
[68243.637802]  [<ffffffffa03e2795>] gre_cisco_rcv+0x75/0xbc [gre]
[68243.708621]  [<ffffffffa03e22f5>] gre_rcv+0x65/0x90 [gre]
[68243.773214]  [<ffffffff816941d8>] ip_local_deliver_finish+0xa8/0x220
[68243.849244]  [<ffffffff816944db>] ip_local_deliver+0x4b/0x90
[68243.916951]  [<ffffffff81693ed1>] ip_rcv_finish+0x121/0x380
[68243.983627]  [<ffffffff816947a6>] ip_rcv+0x286/0x380
[68244.043023]  [<ffffffff8165b80a>] __netif_receive_skb_core+0x61a/0x760
[68244.121122]  [<ffffffff8165b971>] __netif_receive_skb+0x21/0x70
[68244.191942]  [<ffffffff8165c131>] process_backlog+0xb1/0x190
[68244.259642]  [<ffffffff8165ca09>] net_rx_action+0x139/0x280
[68244.326305]  [<ffffffff8107367d>] __do_softirq+0xed/0x360
[68244.390887]  [<ffffffff81073c8e>] irq_exit+0x11e/0x140
[68244.452358]  [<ffffffff8177d873>] do_IRQ+0x63/0xe0
[68244.509674]  [<ffffffff817728ad>] common_interrupt+0x6d/0x6d
[68245.392237] RIP  [<ffffffffa052b4fe>] __skb_pull.part.7+0x4/0x6 [openvswitch]
[68245.520082] ---[ end trace 383bac9f3e676970 ]---

Fixes: aa310701e7 ("openvswitch: Add gre tunnel support.")
Reported-by: Uri Foox <redacted>
CC: Joe Stringer <redacted>
Signed-off-by: Pravin B Shelar <redacted>

Acked-by: Joe Stringer <redacted>