[PATCH net v04] hinic3: Fix skb linearization mismatch and drop skb when skb_checksum_help() failed

[Fan Gong]

Previously, hinic3_send_one_skb() cached the skb fragment count before
calling hinic3_tx_offload(). If hinic3_tx_csum() falls back to
skb_checksum_help() for unsupported tunnel packets, the skb may be
linearized. Continuing to build the TX descriptor with the stale
fragment count leads to a descriptor mismatch, which can trigger
out-of-bounds DMA reads or IOMMU faults.

Furthermore, the old code ignored the return value of skb_checksum_help(),
transmitting corrupted packets with incomplete checksums upon failure.

Fix this by:
1. Moving the hinic3_tx_offload() call before calculating 'num_sge' to
   ensure the correct fragment count is used if the SKB is linearized.
2. Propagating skb_checksum_help() errors and returning
   HINIC3_TX_OFFLOAD_INVALID to properly drop the skb.

Fixes: 17fcb3dc12bb ("hinic3: module initialization and tx/rx logic")
Co-developed-by: Teng Peisen <tengpeisen@xxxxxxxxxx>
Signed-off-by: Teng Peisen <tengpeisen@xxxxxxxxxx>
Co-developed-by: Wu Di <wudi234@xxxxxxxxxx>
Signed-off-by: Wu Di <wudi234@xxxxxxxxxx>
Signed-off-by: Fan Gong <gongfan1@xxxxxxxxxx>
---
 drivers/net/ethernet/huawei/hinic3/hinic3_tx.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/huawei/hinic3/hinic3_tx.c b/drivers/net/ethernet/huawei/hinic3/hinic3_tx.c
index 9306bf0020ca..cc541e7a2318 100644
--- a/drivers/net/ethernet/huawei/hinic3/hinic3_tx.c
+++ b/drivers/net/ethernet/huawei/hinic3/hinic3_tx.c
@@ -261,8 +261,7 @@ static int hinic3_tx_csum(struct hinic3_txq *txq, struct hinic3_sq_task *task,
 		    ((struct udphdr *)skb_transport_header(skb))->dest !=
 		    VXLAN_OFFLOAD_PORT_LE) {
 			/* Unsupported tunnel packet, disable csum offload */
-			skb_checksum_help(skb);
-			return 0;
+			return skb_checksum_help(skb);
 		}
 	}

@@ -412,6 +411,10 @@ static u32 hinic3_tx_offload(struct sk_buff *skb, struct hinic3_sq_task *task,
 		offload |= HINIC3_TX_OFFLOAD_TSO;
 	} else {
 		tso_cs_en = hinic3_tx_csum(txq, task, skb);
+		if (tso_cs_en < 0) {
+			offload = HINIC3_TX_OFFLOAD_INVALID;
+			return offload;
+		}
 		if (tso_cs_en)
 			offload |= HINIC3_TX_OFFLOAD_CSUM;
 	}
@@ -545,6 +548,7 @@ static netdev_tx_t hinic3_send_one_skb(struct sk_buff *skb,
 		skb->len = MIN_SKB_LEN;
 	}

+	offload = hinic3_tx_offload(skb, &task, &queue_info, txq);
 	num_sge = skb_shinfo(skb)->nr_frags + 1;
 	/* assume normal wqe format + 1 wqebb for task info */
 	wqebb_cnt = num_sge + 1;
@@ -560,7 +564,6 @@ static netdev_tx_t hinic3_send_one_skb(struct sk_buff *skb,
 		return NETDEV_TX_BUSY;
 	}

-	offload = hinic3_tx_offload(skb, &task, &queue_info, txq);
 	if (unlikely(offload == HINIC3_TX_OFFLOAD_INVALID)) {
 		goto err_drop_pkt;
 	} else if (!offload) {

base-commit: 2195424c3da2ef1829a63b807e3a900a90e57d85
--
2.54.0