From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	Joshua Hay <joshua.a.hay@intel.com>,
	Emil Tantilov <emil.s.tantilov@intel.com>,
	Aleksandr Loktionov <aleksandr.loktionov@intel.com>,
	Samuel Salin <Samuel.salin@intel.com>,
	Tony Nguyen <anthony.l.nguyen@intel.com>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 6.18 0876/1250] idpf: account for VLAN header when parsing RSC packet header
Date: Thu, 17 Sep 2026 16:11:11 +0100
Message-ID: <20260917151615.723956561@linuxfoundation.org>
In-Reply-To: <20260917151551.901433442@linuxfoundation.org>
References: <20260917151551.901433442@linuxfoundation.org>
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6.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Joshua Hay <joshua.a.hay@intel.com>

[ Upstream commit cc6d60ef92278a31ffc2e94966a0921b9646af18 ]

While parsing the header of a Receive Side Coalesced (RSC) packet, check
if a VLAN tag is present and adjust the header parsing accordingly.
Otherwise, Rx TCP traffic is completely broken for any VLAN interface
whose underlying interface has RSC (rx-gro-hw) enabled.

We only need to worry about one VLAN header since Rx packets with
multiple VLAN headers are not candidates for RSC.

Fixes: 3a8845af66edb ("idpf: add RX splitq napi poll support")
Signed-off-by: Joshua Hay <joshua.a.hay@intel.com>
Reviewed-by: Emil Tantilov <emil.s.tantilov@intel.com>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Tested-by: Samuel Salin <Samuel.salin@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/intel/idpf/idpf_txrx.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/intel/idpf/idpf_txrx.c b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
index 4a4e00c70d93e..813be81682a7d 100644
--- a/drivers/net/ethernet/intel/idpf/idpf_txrx.c
+++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
@@ -3277,6 +3277,7 @@ static int idpf_rx_rsc(struct idpf_rx_queue *rxq, struct sk_buff *skb,
 		       struct libeth_rx_pt decoded)
 {
 	u16 rsc_segments, rsc_seg_len;
+	u16 l3_start = 0;
 	bool ipv4, ipv6;
 	int len;
 
@@ -3299,7 +3300,10 @@ static int idpf_rx_rsc(struct idpf_rx_queue *rxq, struct sk_buff *skb,
 	NAPI_GRO_CB(skb)->count = rsc_segments;
 	skb_shinfo(skb)->gso_size = rsc_seg_len;
 
-	skb_reset_network_header(skb);
+	if (unlikely(eth_type_vlan(skb->protocol)))
+		l3_start = VLAN_HLEN;
+
+	skb_set_network_header(skb, l3_start);
 
 	if (ipv4) {
 		struct iphdr *ipv4h = ip_hdr(skb);
@@ -3307,7 +3311,7 @@ static int idpf_rx_rsc(struct idpf_rx_queue *rxq, struct sk_buff *skb,
 		skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
 
 		/* Reset and set transport header offset in skb */
-		skb_set_transport_header(skb, sizeof(struct iphdr));
+		skb_set_transport_header(skb, l3_start + sizeof(struct iphdr));
 		len = skb->len - skb_transport_offset(skb);
 
 		/* Compute the TCP pseudo header checksum*/
@@ -3317,7 +3321,7 @@ static int idpf_rx_rsc(struct idpf_rx_queue *rxq, struct sk_buff *skb,
 		struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 
 		skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
-		skb_set_transport_header(skb, sizeof(struct ipv6hdr));
+		skb_set_transport_header(skb, l3_start + sizeof(struct ipv6hdr));
 		len = skb->len - skb_transport_offset(skb);
 		tcp_hdr(skb)->check =
 			~tcp_v6_check(len, &ipv6h->saddr, &ipv6h->daddr, 0);
-- 
2.53.0