Xen-netback: Fix issue caused by using gso_type wrongly

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.

V2: use skb_is_gso function as Paul Durrant suggested

Signed-off-by: Annie Li <annie.li@oracle.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 18 insertions, 21 deletions

diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index e5284bca2d90..438d0c09b7e6 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_is_gso(skb)) {
+                        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++;
@@ -338,19 +338,15 @@ static int xenvif_gop_skb(struct sk_buff *skb,
         int head = 1;
         int old_meta_prod;
         int gso_type;
-        int gso_size;
 
         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;
+        if (skb_is_gso(skb)) {
+                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 */
@@ -358,7 +354,7 @@ static int xenvif_gop_skb(struct sk_buff *skb,
                 req = RING_GET_REQUEST(&vif->rx, vif->rx.req_cons++);
                 meta = npo->meta + npo->meta_prod++;
                 meta->gso_type = gso_type;
-                meta->gso_size = gso_size;
+                meta->gso_size = skb_shinfo(skb)->gso_size;
                 meta->size = 0;
                 meta->id = req->id;
         }
@@ -368,7 +364,7 @@ static int xenvif_gop_skb(struct sk_buff *skb,
 
         if ((1 << gso_type) & vif->gso_mask) {
                 meta->gso_type = gso_type;
-                meta->gso_size = gso_size;
+                meta->gso_size = skb_shinfo(skb)->gso_size;
         } else {
                 meta->gso_type = XEN_NETIF_GSO_TYPE_NONE;
                 meta->gso_size = 0;
@@ -500,8 +496,9 @@ 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_is_gso(skb) &&
+                   (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 */