From: Willem de Bruijn <will...@google.com>

skb_warn_bad_offload warns when packets enter the GSO stack that
require skb_checksum_help or vice versa. Do not warn on arbitrary
bad packets. Packet sockets can craft many. Syzkaller was able to
demonstrate another one with eth_type games.

In particular, suppress the warning when segmentation returns an
error, which is for reasons other than checksum offload.

See also commit 36c92474498a ("net: WARN if skb_checksum_help() is
called on skb requiring segmentation") for context on this warning.

Signed-off-by: Willem de Bruijn <will...@google.com>
---
 net/core/dev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 8aa2f70995e8..b0eee49a2489 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2803,7 +2803,7 @@ struct sk_buff *__skb_gso_segment(struct sk_buff *skb,
 
        segs = skb_mac_gso_segment(skb, features);
 
-       if (unlikely(skb_needs_check(skb, tx_path)))
+       if (unlikely(skb_needs_check(skb, tx_path) && !IS_ERR(segs)))
                skb_warn_bad_offload(skb);
 
        return segs;
-- 
2.15.1.424.g9478a66081-goog

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