Commit 21f1b8a6 authored Apr 26, 2019 by Paolo Abeni Committed by David S. Miller Apr 27, 2019

udp: fix GRO reception in case of length mismatch



Currently, the UDP GRO code path does bad things on some edge
conditions - Aggregation can happen even on packet with different
lengths.

Fix the above by rewriting the 'complete' condition for GRO
packets. While at it, note explicitly that we allow merging the
first packet per burst below gso_size.

Reported-by: Sean Tong <seantong114@gmail.com>
Fixes: e20cf8d3 ("udp: implement GRO for plain UDP sockets.")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent fbef9478

net/ipv4/udp_offload.c

+5 −4

Original line number	Diff line number	Diff line
		@@ -377,13 +377,14 @@ static struct sk_buff udp_gro_receive_segment(struct list_head head,

		/* Terminate the flow on len mismatch or if it grow "too much".
		* Under small packet flood GRO count could elsewhere grow a lot
		* leading to execessive truesize values
		* leading to execessive truesize values.
		* On len mismatch merge the first packet shorter than gso_size,
		* otherwise complete the GRO packet.
		*/
		if (!skb_gro_receive(p, skb) &&
		if (uh->len > uh2->len \|\| skb_gro_receive(p, skb) \|\|
		uh->len != uh2->len \|\|
		NAPI_GRO_CB(p)->count >= UDP_GRO_CNT_MAX)
		pp = p;
		else if (uh->len != uh2->len)
		pp = p;

		return pp;
		}

Admin message