gro: take care of DODGY packets

[ Upstream commit d24ef8adf4bf8d0dd6dbea5950039be638c1b2bc ]

Jaroslav reported a recent throughput regression with virtio_net
caused by blamed commit.

It is unclear if DODGY GSO packets coming from user space
can be accepted by GRO engine in the future with minimal
changes, and if there is any expected gain from it.

In the meantime, make sure to detect and flush DODGY packets.

Fixes: e4353daabfb5 ("gro: add support of (hw)gro packets to gro stack")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-and-bisected-by: Jaroslav Pulchart <jaroslav.pulchart@gooddata.com>
Cc: Coco Li <lixiaoyan@google.com>
Cc: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/core/gro.c b/net/core/gro.c
index 8e0fe85a647dab3ebbc1fb9d120e8e4cab6fd87c..1b4abfb9a7a13675603b7d52c15c9ecf6b6a2d1f 100644 (file)
--- a/net/core/gro.c
+++ b/net/core/gro.c
@@ -507,8 +507,9 @@ found_ptype:
        NAPI_GRO_CB(skb)->count = 1;
        if (unlikely(skb_is_gso(skb))) {
                NAPI_GRO_CB(skb)->count = skb_shinfo(skb)->gso_segs;
-               /* Only support TCP at the moment. */
-               if (!skb_is_gso_tcp(skb))
+               /* Only support TCP and non DODGY users. */
+               if (!skb_is_gso_tcp(skb) ||
+                   (skb_shinfo(skb)->gso_type & SKB_GSO_DODGY))
                        NAPI_GRO_CB(skb)->flush = 1;
        }