[PATCH v3 -next] net/core/dev: Warn on a too-short GRO frame

[PATCH v3 -next] net/core/dev: Warn on a too-short GRO frame

[Aaron Conole]

From: Aaron Conole <aconole@bytheb.org>

When signaling that a GRO frame is ready to be processed, the network stack
correctly checks length and aborts processing when a frame is less than 14
bytes. However, such a condition is really indicative of a broken driver,
and should be loudly signaled, rather than silently dropped as the case is
today.

Convert the condition to use net_warn_ratelimited() to ensure the stack
loudly complains about such broken drivers.

Signed-off-by: Aaron Conole <aconole@bytheb.org>
---
v2:
* Switched from WARN_ON to net_warn_ratelimited

v3:
* Amend the string to include device name as a hint

 net/core/dev.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/core/dev.c b/net/core/dev.c
index b9bcbe7..273f10d 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4663,6 +4663,8 @@ static struct sk_buff *napi_frags_skb(struct napi_struct *napi)
 	if (unlikely(skb_gro_header_hard(skb, hlen))) {
 		eth = skb_gro_header_slow(skb, hlen, 0);
 		if (unlikely(!eth)) {
+			net_warn_ratelimited("%s: dropping impossible skb from %s\n",
+					     __func__, napi->dev->name);
 			napi_reuse_skb(napi, skb);
 			return NULL;
 		}
-- 
2.5.5

Re: [PATCH v3 -next] net/core/dev: Warn on a too-short GRO frame

[David Miller]

From: Aaron Conole <aconole@bytheb.org>
Date: Sat,  2 Apr 2016 15:26:43 -0400

> From: Aaron Conole <aconole@bytheb.org>
> 
> When signaling that a GRO frame is ready to be processed, the network stack
> correctly checks length and aborts processing when a frame is less than 14
> bytes. However, such a condition is really indicative of a broken driver,
> and should be loudly signaled, rather than silently dropped as the case is
> today.
> 
> Convert the condition to use net_warn_ratelimited() to ensure the stack
> loudly complains about such broken drivers.
> 
> Signed-off-by: Aaron Conole <aconole@bytheb.org>

Applied, thanks.