4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Bert Kenward <bkenward@xxxxxxxxxxxxxx> [ Upstream commit d4a7a8893d4cdbc89d79ac4aa704bf8d4b67b368 ] The bytes_compl and pkts_compl pointers passed to efx_dequeue_buffers cannot be NULL. Add a paranoid warning to check this condition and fix the one case where they were NULL. efx_enqueue_unwind() is called very rarely, during error handling. Without this fix it would fail with a NULL pointer dereference in efx_dequeue_buffer, with efx_enqueue_skb in the call stack. Fixes: e9117e5099ea ("sfc: Firmware-Assisted TSO version 2") Reported-by: Jarod Wilson <jarod@xxxxxxxxxx> Signed-off-by: Bert Kenward <bkenward@xxxxxxxxxxxxxx> Tested-by: Jarod Wilson <jarod@xxxxxxxxxx> Acked-by: Jarod Wilson <jarod@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/net/ethernet/sfc/tx.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/drivers/net/ethernet/sfc/tx.c +++ b/drivers/net/ethernet/sfc/tx.c @@ -77,6 +77,7 @@ static void efx_dequeue_buffer(struct ef } if (buffer->flags & EFX_TX_BUF_SKB) { + EFX_WARN_ON_PARANOID(!pkts_compl || !bytes_compl); (*pkts_compl)++; (*bytes_compl) += buffer->skb->len; dev_consume_skb_any((struct sk_buff *)buffer->skb); @@ -426,12 +427,14 @@ static int efx_tx_map_data(struct efx_tx static void efx_enqueue_unwind(struct efx_tx_queue *tx_queue) { struct efx_tx_buffer *buffer; + unsigned int bytes_compl = 0; + unsigned int pkts_compl = 0; /* Work backwards until we hit the original insert pointer value */ while (tx_queue->insert_count != tx_queue->write_count) { --tx_queue->insert_count; buffer = __efx_tx_queue_get_insert_buffer(tx_queue); - efx_dequeue_buffer(tx_queue, buffer, NULL, NULL); + efx_dequeue_buffer(tx_queue, buffer, &pkts_compl, &bytes_compl); } }