[PATCH iwl-net v2] e1000e: fix Tx descriptor field wrapping

[Matt Vollrath <tactii@gmail.com>]

When an skb arrives at the driver and the header length exceeds the u8
hdr_len, tucss and tucso fields in e1000_context_desc, wrapped values
are sent to the card. If TSO is enabled, some header lengths will cause
the card to hang.

This was reproduced on an I218-V with an unprivileged Python script.

Fix it by disabling GSO and checksum offload when the header length (and
checksum offset) would exceed the field widths. Compensate for a
software-inserted VLAN tag.

Because of a quirk in the ordering of ndo_features_check, the skb's
transport_header field may be stale. If the skb carries
CHECKSUM_PARTIAL, use csum_start to find the header. Otherwise, there's
no reliable interface, so don't offload it.

Fixes: bc7f75fa9788 ("[E1000E]: New pci-express e1000 driver (currently for ICH9 devices only)")
Cc: stable@vger.kernel.org
Assisted-by: LLM
Signed-off-by: Matt Vollrath <tactii@gmail.com>
---
 drivers/net/ethernet/intel/e1000e/netdev.c | 34 +++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
index 6f85dab5c55c5..370776657d100 100644
--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -7355,6 +7355,38 @@ static int e1000_set_features(struct net_device *netdev,
 	return 1;
 }
 
+static netdev_features_t e1000_features_check(struct sk_buff *skb,
+					      struct net_device *netdev,
+					      netdev_features_t features)
+{
+	/* Do not offload packets whose header lengths exceed the u8 fields
+	 * in the descriptor.
+	 */
+	unsigned int hdr_len = 0;
+
+	if (skb->ip_summed == CHECKSUM_PARTIAL) {
+		const struct tcphdr *th = (const void *)skb_checksum_start(skb);
+
+		hdr_len = skb_checksum_start_offset(skb);
+		if (skb_is_gso(skb) && skb_is_gso_tcp(skb))
+			hdr_len += __tcp_hdrlen(th);
+		else
+			hdr_len += skb->csum_offset;
+	} else if (skb_is_gso(skb)) {
+		/* Work around untrustworthy header offsets in this case. */
+		return features & ~(NETIF_F_CSUM_MASK | NETIF_F_GSO_MASK);
+	}
+
+	if (skb_vlan_tag_present(skb) &&
+	    !vlan_hw_offload_capable(features, skb->vlan_proto))
+		hdr_len += VLAN_HLEN;
+
+	if (hdr_len > U8_MAX)
+		features &= ~(NETIF_F_CSUM_MASK | NETIF_F_GSO_MASK);
+
+	return features;
+}
+
 static const struct net_device_ops e1000e_netdev_ops = {
 	.ndo_open		= e1000e_open,
 	.ndo_stop		= e1000e_close,
@@ -7374,7 +7406,7 @@ static const struct net_device_ops e1000e_netdev_ops = {
 #endif
 	.ndo_set_features	= e1000_set_features,
 	.ndo_fix_features	= e1000_fix_features,
-	.ndo_features_check	= passthru_features_check,
+	.ndo_features_check	= e1000_features_check,
 	.ndo_hwtstamp_get	= e1000e_hwtstamp_get,
 	.ndo_hwtstamp_set	= e1000e_hwtstamp_set,
 };

base-commit: 7076f684d5132e6a6145e1da2fa74771ecd052e5
-- 
2.43.0