net_sched: better precise estimation on packet length for untrusted packets

[ Upstream commit 15e5a030716468dce4032fa0f398d840fa2756f6 ]

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().

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

diff --git a/net/core/dev.c b/net/core/dev.c
index 9a278e9304262e6be24a7c890009cb4646d41bbb..c9eb9e6be87fe171a7749178e63d83973d739362 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2592,6 +2592,7 @@ 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);
@@ -2601,7 +2602,12 @@ 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;
        }
 }