net: WARN if skb_checksum_help() is called on skb requiring segmentation

skb_checksum_help() has never done anything useful with skbs that
require segmentation.  Setting skb->ip_summed = CHECKSUM_NONE makes
them invalid and provokes a later WARNing in skb_gso_segment().

Passing such an skb to skb_checksum_help() indicates a bug, so we
should warn about it immediately.  Move the warning from
skb_gso_segment() into a shared function, and add gso_type and
gso_size to it.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 19 insertions, 12 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index 7e6b7dcaacde..17db2f2e5236 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1887,6 +1887,22 @@ void skb_set_dev(struct sk_buff *skb, struct net_device *dev)
 EXPORT_SYMBOL(skb_set_dev);
 #endif /* CONFIG_NET_NS */
 
+static void skb_warn_bad_offload(const struct sk_buff *skb)
+{
+        struct net_device *dev = skb->dev;
+        const char *driver = "";
+
+        if (dev && dev->dev.parent)
+                driver = dev_driver_string(dev->dev.parent);
+
+        WARN(1, "%s: caps=(%pNF, %pNF) len=%d data_len=%d gso_size=%d "
+             "gso_type=%d ip_summed=%d\n",
+             driver, dev ? &dev->features : NULL,
+             skb->sk ? &skb->sk->sk_route_caps : NULL,
+             skb->len, skb->data_len, skb_shinfo(skb)->gso_size,
+             skb_shinfo(skb)->gso_type, skb->ip_summed);
+}
+
 /*
  * Invalidate hardware checksum when packet is to be mangled, and
  * complete checksum manually on outgoing path.
@@ -1900,8 +1916,8 @@ int skb_checksum_help(struct sk_buff *skb)
                 goto out_set_summed;
 
         if (unlikely(skb_shinfo(skb)->gso_size)) {
-                /* Let GSO fix up the checksum. */
-                goto out_set_summed;
+                skb_warn_bad_offload(skb);
+                return -EINVAL;
         }
 
         offset = skb_checksum_start_offset(skb);
@@ -1961,16 +1977,7 @@ struct sk_buff *skb_gso_segment(struct sk_buff *skb,
         __skb_pull(skb, skb->mac_len);
 
         if (unlikely(skb->ip_summed != CHECKSUM_PARTIAL)) {
-                struct net_device *dev = skb->dev;
-                const char *driver = "";
-
-                if (dev && dev->dev.parent)
-                        driver = dev_driver_string(dev->dev.parent);
-
-                WARN(1, "%s: caps=(%pNF, %pNF) len=%d data_len=%d ip_summed=%d\n",
-                     driver, dev ? &dev->features : NULL,
-                     skb->sk ? &skb->sk->sk_route_caps : NULL,
-                     skb->len, skb->data_len, skb->ip_summed);
+                skb_warn_bad_offload(skb);
 
                 if (skb_header_cloned(skb) &&
                     (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))