[PATCH net-next 3/3] net: skb: add compatibility warnings to skb_shift()

[Jakub Kicinski <kuba@kernel.org>]

According to current semantics we should never try to shift data
between skbs which differ on decrypted or pp_recycle status.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
 net/core/skbuff.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 466999a7515e..c8ac79851cd6 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -4139,6 +4139,9 @@ int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen)
 	if (skb_zcopy(tgt) || skb_zcopy(skb))
 		return 0;
 
+	DEBUG_NET_WARN_ON_ONCE(tgt->pp_recycle != skb->pp_recycle);
+	DEBUG_NET_WARN_ON_ONCE(skb_cmp_decrypted(tgt, skb));
+
 	todo = shiftlen;
 	from = 0;
 	to = skb_shinfo(tgt)->nr_frags;
-- 
2.45.1