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bnx2x: fix header length calculation for encapsulated TSO

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Commit 80bfab79b8 ("net: adopt skb_network_offset() and similar helpers")
replaced the difference between the inner transport header and the outer
network header with skb_inner_transport_offset().
The helper is relative to skb->data, so the new calculation incorrectly
includes the outer Ethernet header in fw_ip_hdr_to_payload_w.

On a BCM57810 transmitting TCP over VXLAN with an outer MTU of 1500,
hardware segmentation emits packets declaring an outer IPv4 total length
of 1514 while the actual IP packet is only 1500 bytes long. The receiver
drops these malformed packets, severely degrading TCP connectivity.

Subtract skb_network_offset() to restore the original calculation of the
length from the outer network header to the inner TCP payload.

Reproduced with plain kernel VXLAN and one TCP flow on kernel
7.0.0-31-generic: 50 of 200 captured packets had an invalid outer IP length
with the original driver, versus none with this fix. Disabling TSO/GSO on
the test VXLAN device also eliminated the error with the original driver.

Fixes: 80bfab79b8 ("net: adopt skb_network_offset() and similar helpers")
Signed-off-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20261009-bnx2x-tso-fix-v1-1-1ebea422422d@gmelikov.ru
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
George Melikov 2026-10-09 20:30:18 +03:00 committed by Jakub Kicinski
parent 50f2103fce
commit 4fc1d5bb44
1 changed files with 2 additions and 1 deletions
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3
drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c
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@ -3666,7 +3666,8 @@ static void bnx2x_update_pbds_gso_enc(struct sk_buff *skb,
u8 outerip_off, outerip_len = 0;
/* from outer IP to transport */
hlen_w = skb_inner_transport_offset(skb) >> 1;
hlen_w = (skb_inner_transport_offset(skb) -
skb_network_offset(skb)) >> 1;
/* transport len */
hlen_w += inner_tcp_hdrlen(skb) >> 1;