From 6ae459bdaaeebc632b16e54dcbabb490c6931d61 Mon Sep 17 00:00:00 2001 From: Pravin B Shelar Date: Tue, 22 Sep 2015 12:57:53 -0700 Subject: [PATCH] skbuff: Fix skb checksum flag on skb pull VXLAN device can receive skb with checksum partial. But the checksum offset could be in outer header which is pulled on receive. This results in negative checksum offset for the skb. Such skb can cause the assert failure in skb_checksum_help(). Following patch fixes the bug by setting checksum-none while pulling outer header. Following is the kernel panic msg from old kernel hitting the bug. ------------[ cut here ]------------ kernel BUG at net/core/dev.c:1906! RIP: 0010:[] skb_checksum_help+0x144/0x150 Call Trace: [] queue_userspace_packet+0x408/0x470 [openvswitch] [] ovs_dp_upcall+0x5d/0x60 [openvswitch] [] ovs_dp_process_packet_with_key+0xe6/0x100 [openvswitch] [] ovs_dp_process_received_packet+0x4b/0x80 [openvswitch] [] ovs_vport_receive+0x2a/0x30 [openvswitch] [] vxlan_rcv+0x53/0x60 [openvswitch] [] vxlan_udp_encap_recv+0x8b/0xf0 [openvswitch] [] udp_queue_rcv_skb+0x2dc/0x3b0 [] __udp4_lib_rcv+0x1cf/0x6c0 [] udp_rcv+0x1a/0x20 [] ip_local_deliver_finish+0xdd/0x280 [] ip_local_deliver+0x88/0x90 [] ip_rcv_finish+0x10d/0x370 [] ip_rcv+0x235/0x300 [] __netif_receive_skb+0x55d/0x620 [] netif_receive_skb+0x80/0x90 [] virtnet_poll+0x555/0x6f0 [] net_rx_action+0x134/0x290 [] __do_softirq+0xa8/0x210 [] call_softirq+0x1c/0x30 [] do_softirq+0x65/0xa0 [] irq_exit+0x8e/0xb0 [] do_IRQ+0x63/0xe0 [] common_interrupt+0x6e/0x6e Reported-by: Anupam Chanda Signed-off-by: Pravin B Shelar Acked-by: Tom Herbert Signed-off-by: David S. Miller --- include/linux/skbuff.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 9987af080fa0..2b0a30a6e31c 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -2707,6 +2707,9 @@ static inline void skb_postpull_rcsum(struct sk_buff *skb, { if (skb->ip_summed == CHECKSUM_COMPLETE) skb->csum = csum_sub(skb->csum, csum_partial(start, len, 0)); + else if (skb->ip_summed == CHECKSUM_PARTIAL && + skb_checksum_start_offset(skb) <= len) + skb->ip_summed = CHECKSUM_NONE; } unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len); -- 2.20.1