[Xen-devel] [PATCH net] Xen-netback: Fix issue caused by using gso_type wrongly

[Annie Li <Annie.li@xxxxxxxxxx>]

From: Annie Li <annie.li@xxxxxxxxxx>

Current netback uses gso_type to check whether the skb contains
gso offload, and this is wrong. Gso_size is the right one to
check gso existence, and gso_type is only used to check gso type.

Some skbs contains nonzero gso_type and zero gso_size, current
netback would treat these skbs as gso and create wrong response
for this. This also causes ssh failure to domu from other server.

Signed-off-by: Annie Li <annie.li@xxxxxxxxxx>
---
 drivers/net/xen-netback/netback.c |   35 +++++++++++++++++------------------
 1 files changed, 17 insertions(+), 18 deletions(-)

diff --git a/drivers/net/xen-netback/netback.c 
b/drivers/net/xen-netback/netback.c
index e5284bc..57a7d5d 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -240,7 +240,7 @@ static void xenvif_gop_frag_copy(struct xenvif *vif, struct 
sk_buff *skb,
        struct gnttab_copy *copy_gop;
        struct xenvif_rx_meta *meta;
        unsigned long bytes;
-       int gso_type;
+       int gso_type = XEN_NETIF_GSO_TYPE_NONE;
 
        /* Data must not cross a page boundary. */
        BUG_ON(size + offset > PAGE_SIZE<<compound_order(page));
@@ -299,12 +299,12 @@ static void xenvif_gop_frag_copy(struct xenvif *vif, 
struct sk_buff *skb,
                }
 
                /* Leave a gap for the GSO descriptor. */
-               if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
-                       gso_type = XEN_NETIF_GSO_TYPE_TCPV4;
-               else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
-                       gso_type = XEN_NETIF_GSO_TYPE_TCPV6;
-               else
-                       gso_type = XEN_NETIF_GSO_TYPE_NONE;
+               if (skb_shinfo(skb)->gso_size) {
+                       if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
+                               gso_type = XEN_NETIF_GSO_TYPE_TCPV4;
+                       else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
+                               gso_type = XEN_NETIF_GSO_TYPE_TCPV6;
+               }
 
                if (*head && ((1 << gso_type) & vif->gso_mask))
                        vif->rx.req_cons++;
@@ -342,15 +342,13 @@ static int xenvif_gop_skb(struct sk_buff *skb,
 
        old_meta_prod = npo->meta_prod;
 
-       if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4) {
-               gso_type = XEN_NETIF_GSO_TYPE_TCPV4;
-               gso_size = skb_shinfo(skb)->gso_size;
-       } else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6) {
-               gso_type = XEN_NETIF_GSO_TYPE_TCPV6;
-               gso_size = skb_shinfo(skb)->gso_size;
-       } else {
-               gso_type = XEN_NETIF_GSO_TYPE_NONE;
-               gso_size = 0;
+       gso_type = XEN_NETIF_GSO_TYPE_NONE;
+       gso_size = skb_shinfo(skb)->gso_size;
+       if (gso_size) {
+               if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
+                       gso_type = XEN_NETIF_GSO_TYPE_TCPV4;
+               else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
+                       gso_type = XEN_NETIF_GSO_TYPE_TCPV6;
        }
 
        /* Set up a GSO prefix descriptor, if necessary */
@@ -500,8 +498,9 @@ static void xenvif_rx_action(struct xenvif *vif)
                        size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
                        max_slots_needed += DIV_ROUND_UP(size, PAGE_SIZE);
                }
-               if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4 ||
-                   skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
+               if (skb_shinfo(skb)->gso_size &&
+                  (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4 ||
+                   skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6))
                        max_slots_needed++;
 
                /* If the skb may not fit then bail out now */
-- 
1.7.3.4


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