On Tue, Feb 12, 2019 at 06:47:30PM +0800, Xin Long wrote: > Jianlin reported a panic when running sctp gso over gre over vlan device: > > [ 84.772930] RIP: 0010:do_csum+0x6d/0x170 > [ 84.790605] Call Trace: > [ 84.791054] csum_partial+0xd/0x20 > [ 84.791657] gre_gso_segment+0x2c3/0x390 > [ 84.792364] inet_gso_segment+0x161/0x3e0 > [ 84.793071] skb_mac_gso_segment+0xb8/0x120 > [ 84.793846] __skb_gso_segment+0x7e/0x180 > [ 84.794581] validate_xmit_skb+0x141/0x2e0 > [ 84.795297] __dev_queue_xmit+0x258/0x8f0 > [ 84.795949] ? eth_header+0x26/0xc0 > [ 84.796581] ip_finish_output2+0x196/0x430 > [ 84.797295] ? skb_gso_validate_network_len+0x11/0x80 > [ 84.798183] ? ip_finish_output+0x169/0x270 > [ 84.798875] ip_output+0x6c/0xe0 > [ 84.799413] ? ip_append_data.part.50+0xc0/0xc0 > [ 84.800145] iptunnel_xmit+0x144/0x1c0 > [ 84.800814] ip_tunnel_xmit+0x62d/0x930 [ip_tunnel] > [ 84.801699] gre_tap_xmit+0xac/0xf0 [ip_gre] > [ 84.802395] dev_hard_start_xmit+0xa5/0x210 > [ 84.803086] sch_direct_xmit+0x14f/0x340 > [ 84.803733] __dev_queue_xmit+0x799/0x8f0 > [ 84.804472] ip_finish_output2+0x2e0/0x430 > [ 84.805255] ? skb_gso_validate_network_len+0x11/0x80 > [ 84.806154] ip_output+0x6c/0xe0 > [ 84.806721] ? ip_append_data.part.50+0xc0/0xc0 > [ 84.807516] sctp_packet_transmit+0x716/0xa10 [sctp] > [ 84.808337] sctp_outq_flush+0xd7/0x880 [sctp] > > It was caused by SKB_GSO_CB(skb)->csum_start not set in sctp_gso_segment. > sctp_gso_segment() calls skb_segment() with 'feature | NETIF_F_HW_CSUM', > which causes SKB_GSO_CB(skb)->csum_start not to be set in skb_segment(). > > For TCP/UDP, when feature supports HW_CSUM, CHECKSUM_PARTIAL will be set > and gso_reset_checksum will be called to set SKB_GSO_CB(skb)->csum_start. > > So SCTP should do the same as TCP/UDP, to call gso_reset_checksum() when > computing checksum in sctp_gso_segment. > > Reported-by: Jianlin Shi <jishi@xxxxxxxxxx> > Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx> Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx> > --- > net/sctp/offload.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/net/sctp/offload.c b/net/sctp/offload.c > index 123e9f2..edfcf16 100644 > --- a/net/sctp/offload.c > +++ b/net/sctp/offload.c > @@ -36,6 +36,7 @@ static __le32 sctp_gso_make_checksum(struct sk_buff *skb) > { > skb->ip_summed = CHECKSUM_NONE; > skb->csum_not_inet = 0; > + gso_reset_checksum(skb, ~0); > return sctp_compute_cksum(skb, skb_transport_offset(skb)); > } > > -- > 2.1.0 >