6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit 83769c23fb1879edc916a526ba424285033baf2d ] gve_can_send_tso() computes how many buffers each segment of a GSO packet would span, and for this it needs the length of the headers that the device replicates in front of every segment. It unconditionally uses skb_tcp_all_headers(), which reads the doff field of the TCP header. SKB_GSO_UDP_L4 packets have no TCP header: tcp_hdrlen() then reads one byte of the UDP payload, and header_len can be anything in [0, 60] instead of the transport offset plus the eight bytes of the UDP header that gve_prep_tso() programs into the TSO context descriptor. A wrong header length shifts all the segment boundaries computed in the loop, so the number of buffers per segment can be over or under estimated. In the first case, GSO is needlessly disabled for this packet by gve_features_check_dqo() and the stack has to segment it. In the second case, the driver hands the device a packet whose segments span more than GVE_TX_MAX_DATA_DESCS buffers. Use the UDP header length for SKB_GSO_UDP_L4 packets, matching what gve_prep_tso() does. Fixes: 014c607f86ab ("gve: add support for UDP GSO for DQO format") Closes: https://lore.kernel.org/netdev/CANn89i+MS4L60sFQ49=-f-mibeveUfcrpVkD5X+Qy6SOnEpd6w@mail.gmail.com/ Signed-off-by: Eric Dumazet Cc: Ankit Garg Cc: Harshitha Ramamurthy Cc: Joshua Washington Cc: Willem de Bruijn Reviewed-by: Ankit Garg Reviewed-by: Harshitha Ramamurthy Link: https://patch.msgid.link/20260923145942.731365-1-edumazet@google.com Signed-off-by: Jakub Kicinski Stable-dep-of: 3b430ea62340 ("gve: fix TX drop when GSO MSS is too small for hw") Signed-off-by: Sasha Levin --- drivers/net/ethernet/google/gve/gve_tx_dqo.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/google/gve/gve_tx_dqo.c b/drivers/net/ethernet/google/gve/gve_tx_dqo.c index 9c5f03ac3c35f..49ed911957ec0 100644 --- a/drivers/net/ethernet/google/gve/gve_tx_dqo.c +++ b/drivers/net/ethernet/google/gve/gve_tx_dqo.c @@ -923,13 +923,19 @@ static bool gve_can_send_tso(const struct sk_buff *skb) { const int max_bufs_per_seg = GVE_TX_MAX_DATA_DESCS - 1; const struct skb_shared_info *shinfo = skb_shinfo(skb); - const int header_len = skb_tcp_all_headers(skb); const int gso_size = shinfo->gso_size; int cur_seg_num_bufs; int prev_frag_size; int cur_seg_size; + int header_len; int i; + /* Must match the header length programmed by gve_prep_tso(). */ + if (skb_is_gso_tcp(skb)) + header_len = skb_tcp_all_headers(skb); + else + header_len = skb_transport_offset(skb) + sizeof(struct udphdr); + cur_seg_size = skb_headlen(skb) - header_len; prev_frag_size = skb_headlen(skb); cur_seg_num_bufs = cur_seg_size > 0; -- 2.53.0