From: Willem de Bruijn willemb@google.com
[ Upstream commit 6cd021a58c18a1731f7e47f83e172c0c302d65e5 ]
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: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/net/udp.h | 3 +++ 1 file changed, 3 insertions(+)
--- a/include/net/udp.h +++ b/include/net/udp.h @@ -476,6 +476,9 @@ static inline struct sk_buff *udp_rcv_se 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 */