[PATCH net v2 3/4] net: renesas: rswitch: fix leaked pointer on error path

[Nikita Yushchenko]

If error path is taken while filling descriptor for a frame, skb
pointer is left in the entry. Later, on the ring entry reuse, the
same entry could be used as a part of a multi-descriptor frame,
and skb for that new frame could be stored in a different entry.

Then, the stale pointer will reach the completion routine, and passed
to the release operation.

Fix that by clearing the saved skb pointer at the error path.

Fixes: d2c96b9d5f83 ("net: rswitch: Add jumbo frames handling for TX")
Signed-off-by: Nikita Yushchenko <nikita.yoush@xxxxxxxxxxxxxxxxxx>
---
 drivers/net/ethernet/renesas/rswitch.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/ethernet/renesas/rswitch.c b/drivers/net/ethernet/renesas/rswitch.c
index 800744a6c25b..9c55f3480678 100644
--- a/drivers/net/ethernet/renesas/rswitch.c
+++ b/drivers/net/ethernet/renesas/rswitch.c
@@ -1704,6 +1704,7 @@ static netdev_tx_t rswitch_start_xmit(struct sk_buff *skb, struct net_device *nd
 	return ret;
 
 err_unmap:
+	gq->skbs[(gq->cur + nr_desc - 1) % gq->ring_size] = NULL;
 	dma_unmap_single(ndev->dev.parent, dma_addr_orig, skb->len, DMA_TO_DEVICE);
 
 err_kfree:
-- 
2.39.5