net: renesas: rswitch: fix leaked pointer on error path

[ Upstream commit bb617328bafa1023d8e9c25a25345a564c66c14f ]

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@cogentembedded.com>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Link: https://patch.msgid.link/20241208095004.69468-4-nikita.yoush@cogentembedded.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/ethernet/renesas/rswitch.c b/drivers/net/ethernet/renesas/rswitch.c
index c251becef6f84fcd3a70aeabeb70d05ce989b61e..af0bc95ad6aee92f3bb658453d89a39b883a8747 100644 (file)
--- a/drivers/net/ethernet/renesas/rswitch.c
+++ b/drivers/net/ethernet/renesas/rswitch.c
@@ -1703,6 +1703,7 @@ 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: