| From bbac07b46d9e372a4faf78fca7c7df0449acd086 Mon Sep 17 00:00:00 2001 |
| From: Willem de Bruijn <willemb@google.com> |
| Date: Mon, 27 Jan 2020 15:40:31 -0500 |
| Subject: [PATCH] udp: segment looped gso packets correctly |
| |
| commit 6cd021a58c18a1731f7e47f83e172c0c302d65e5 upstream. |
| |
| Multicast and broadcast packets can be looped from egress to ingress |
| pre segmentation with dev_loopback_xmit. That function unconditionally |
| sets ip_summed to CHECKSUM_UNNECESSARY. |
| |
| udp_rcv_segment segments gso packets in the udp rx path. Segmentation |
| usually executes on egress, and does not expect packets of this type. |
| __udp_gso_segment interprets !CHECKSUM_PARTIAL as CHECKSUM_NONE. But |
| the offsets are not correct for gso_make_checksum. |
| |
| UDP GSO packets are of type CHECKSUM_PARTIAL, with their uh->check set |
| to the correct pseudo header checksum. Reset ip_summed to this type. |
| (CHECKSUM_PARTIAL is allowed on ingress, see comments in skbuff.h) |
| |
| Reported-by: syzbot <syzkaller@googlegroups.com> |
| Fixes: cf329aa42b66 ("udp: cope with UDP GRO packet misdirection") |
| Signed-off-by: Willem de Bruijn <willemb@google.com> |
| Signed-off-by: David S. Miller <davem@davemloft.net> |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/include/net/udp.h b/include/net/udp.h |
| index 79d141d2103b..3c1ffa95e733 100644 |
| --- a/include/net/udp.h |
| +++ b/include/net/udp.h |
| @@ -476,6 +476,9 @@ static inline struct sk_buff *udp_rcv_segment(struct sock *sk, |
| if (!inet_get_convert_csum(sk)) |
| features |= NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM; |
| |
| + if (skb->pkt_type == PACKET_LOOPBACK) |
| + skb->ip_summed = CHECKSUM_PARTIAL; |
| + |
| /* the GSO CB lays after the UDP one, no need to save and restore any |
| * CB fragment |
| */ |
| -- |
| 2.7.4 |
| |
