From 15989abd74f16f44bf953d056b95f1d2fda9b0cd Mon Sep 17 00:00:00 2001 From: Lorenzo Bianconi Date: Fri, 11 Sep 2026 11:20:15 +0200 Subject: [PATCH] net: stmmac: fix TSO header length truncation stmmac_tso_xmit() stores the protocol header length returned by stmmac_tso_header_size() in a u8. stmmac_tso_valid_packet() admits headers up to 1023 bytes, so a header longer than 255 bytes wraps modulo 256 (486 becomes 230, 256 becomes 0). A TCP over IPv6 socket carrying a few hundred bytes of sticky destination/hop-by-hop options makes skb_tcp_all_headers() exceed 255 while staying below the 1023-byte limit, so such an skb reaches stmmac_tso_xmit(). Widen proto_hdr_len to unsigned int, which is sufficient since the value is bounded by the hardware limit, and adjust the debug print specifier accordingly. Fixes: 9edfa7dab811 ("net: stmmac: enable TSO for IPv6") Signed-off-by: Lorenzo Bianconi Reviewed-by: Maxime Chevallier Link: https://patch.msgid.link/20260911-stmmac-fix-header-length-v1-1-8fc103334327@oss.qualcomm.com Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c index 62c3441911e7..1fb5f804ea23 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c @@ -4513,16 +4513,16 @@ static int stmmac_tso_get_num_desc(struct stmmac_tx_queue *tx_q, */ static netdev_tx_t stmmac_tso_xmit(struct sk_buff *skb, struct net_device *dev) { + unsigned int first_entry, entry, tx_packets, proto_hdr_len; struct dma_desc *desc, *first, *mss_desc = NULL; struct stmmac_priv *priv = netdev_priv(dev); - unsigned int first_entry, entry, tx_packets; struct stmmac_txq_stats *txq_stats; int i, first_tx, nfrags, ndesc; struct stmmac_tx_queue *tx_q; bool set_ic, is_last_segment; u32 pay_len, mss, queue; - u8 proto_hdr_len, hdr; dma_addr_t des; + u8 hdr; nfrags = skb_shinfo(skb)->nr_frags; queue = skb_get_queue_mapping(skb); @@ -4570,7 +4570,7 @@ static netdev_tx_t stmmac_tso_xmit(struct sk_buff *skb, struct net_device *dev) } if (netif_msg_tx_queued(priv)) { - pr_info("%s: hdrlen %d, hdr_len %d, pay_len %d, mss %d\n", + pr_info("%s: hdrlen %d, hdr_len %u, pay_len %d, mss %d\n", __func__, hdr, proto_hdr_len, pay_len, mss); pr_info("\tskb->len %d, skb->data_len %d\n", skb->len, skb->data_len);