netdev - [PATCH net-next] net: add a debug check in __skb

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Message-ID: <20260130160253.2936789-1-edumazet@google.com>
Date: Fri, 30 Jan 2026 16:02:53 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: Simon Horman <horms@...nel.org>, netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next] net: add a debug check in __skb_push()

Add the following check, to detect bugs sooner for CONFIG_DEBUG_NET=y
builds.

	DEBUG_NET_WARN_ON_ONCE(skb->data < skb->head);

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 include/linux/skbuff.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index e6bfe5d0c5252b2e7540e1fef9317aab83feced2..8b399ddf1b9bd0dddb37f417ccfa5ea675efafa3 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2813,6 +2813,7 @@ static inline void *__skb_push(struct sk_buff *skb, unsigned int len)
 	DEBUG_NET_WARN_ON_ONCE(len > INT_MAX);
 
 	skb->data -= len;
+	DEBUG_NET_WARN_ON_ONCE(skb->data < skb->head);
 	skb->len  += len;
 	return skb->data;
 }
-- 
2.53.0.rc1.225.gd81095ad13-goog