net_sched: better precise estimation on packet length for untrusted packets

gso_segs were reset to zero when kernel receive packets from untrusted
source. But we use this zero value to estimate precise packet len which is
wrong. So this patch tries to estimate the correct gso_segs value before using
it in qdisc_pkt_len_init().

Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 1 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index de930b751712..f5ad23bb24fc 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2588,6 +2588,7 @@ static void qdisc_pkt_len_init(struct sk_buff *skb)
          */
         if (shinfo->gso_size)  {
                 unsigned int hdr_len;
+                u16 gso_segs = shinfo->gso_segs;
 
                 /* mac layer + network layer */
                 hdr_len = skb_transport_header(skb) - skb_mac_header(skb);
@@ -2597,7 +2598,12 @@ static void qdisc_pkt_len_init(struct sk_buff *skb)
                         hdr_len += tcp_hdrlen(skb);
                 else
                         hdr_len += sizeof(struct udphdr);
-                qdisc_skb_cb(skb)->pkt_len += (shinfo->gso_segs - 1) * hdr_len;
+
+                if (shinfo->gso_type & SKB_GSO_DODGY)
+                        gso_segs = DIV_ROUND_UP(skb->len - hdr_len,
+                                                shinfo->gso_size);
+
+                qdisc_skb_cb(skb)->pkt_len += (gso_segs - 1) * hdr_len;
         }
 }