[PATCH 4.14 095/146] sfc: pass valid pointers from efx_enqueue_unwind

Greg Kroah-Hartman
2018-01-01T14:57:55Z

From: Bert Kenward <bkenward@solarflare.com>

[ 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@redhat.com>
Signed-off-by: Bert Kenward <bkenward@solarflare.com>
Tested-by: Jarod Wilson <jarod@redhat.com>
Acked-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
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);
}
}