From 2170a1f091486c2b5726a43c97a7d4b72073811c Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 7 Jan 2025 14:43:42 +0000 Subject: [PATCH] net: no longer reset transport_header in __netif_receive_skb_core() In commit 66e4c8d95008 ("net: warn if transport header was not set") I added a debug check in skb_transport_header() to detect if a caller expects the transport_header to be set to a meaningful value by a prior code path. Unfortunately, __netif_receive_skb_core() resets the transport header to the same value than the network header, defeating this check in receive paths. Pretending the transport and network headers are the same is usually wrong. This patch removes this reset for CONFIG_DEBUG_NET=y builds to let fuzzers and CI find bugs. Signed-off-by: Eric Dumazet Reviewed-by: Simon Horman Link: https://patch.msgid.link/20250107144342.499759-1-edumazet@google.com Signed-off-by: Paolo Abeni --- net/core/dev.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/net/core/dev.c b/net/core/dev.c index efbe2c4d9458..983c24927316 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -5493,8 +5493,14 @@ static int __netif_receive_skb_core(struct sk_buff **pskb, bool pfmemalloc, orig_dev = skb->dev; skb_reset_network_header(skb); +#if !defined(CONFIG_DEBUG_NET) + /* We plan to no longer reset the transport header here. + * Give some time to fuzzers and dev build to catch bugs + * in network stacks. + */ if (!skb_transport_header_was_set(skb)) skb_reset_transport_header(skb); +#endif skb_reset_mac_len(skb); pt_prev = NULL; -- 2.49.0