| Message ID | 20250107144342.499759-1-edumazet@google.com (mailing list archive) |
|---|---|
| State | New |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net-next] net: no longer reset transport_header in __netif_receive_skb_core() | expand |
On Tue, Jan 07, 2025 at 02:43:42PM +0000, Eric Dumazet wrote: > 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 <edumazet@google.com> Reviewed-by: Simon Horman <horms@kernel.org>
diff --git a/net/core/dev.c b/net/core/dev.c index 073f682a9653a212198b12bae17fafe7b46f96e9..d2b6b3b96459159dc6fbd34143821516e9d0c5bd 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -5476,8 +5476,14 @@ 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;
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 <edumazet@google.com> --- net/core/dev.c | 6 ++++++ 1 file changed, 6 insertions(+)