Re: [PATCH net-next v5 10/14] net: renesas: rswitch: update port HW init

[Jakub Kicinski <kuba@kernel.org>]

This is an AI-generated review of your patch. The human sending this
email has considered the AI review valid, or at least plausible.
---
net: renesas: rswitch: update port HW init

Certain Ethernet and cpu port settings need to be updated for vlan
support.

> diff --git a/drivers/net/ethernet/renesas/rswitch_main.c b/drivers/net/ethernet/renesas/rswitch_main.c
> index a445d9a8505d8..13e59d2d08282 100644
> --- a/drivers/net/ethernet/renesas/rswitch_main.c
> +++ b/drivers/net/ethernet/renesas/rswitch_main.c

[ ... ]

> @@ -895,6 +899,7 @@ static bool rswitch_rx(struct net_device *ndev, int *quota)
>  	limit = boguscnt;
>  
>  	desc = &gq->rx_ring[gq->cur];
> +
>  	while ((desc->desc.die_dt & DT_MASK) != DT_FEMPTY) {
>  		dma_rmb();
>  		skb = rswitch_rx_handle_desc(ndev, gq, desc);

[Severity: High]
This is a pre-existing issue, but does this code leak receive buffer
fragments allocated via netdev_alloc_frag() when packet assembly fails?

In rswitch_rx_handle_desc(), if build_skb() fails for a start fragment,
or if a middle/end fragment arrives without a preceding start fragment,
the function returns NULL.

The caller rswitch_rx() then jumps to the out label:

	skb = rswitch_rx_handle_desc(ndev, gq, desc);
	if (!skb)
		goto out;
	...
out:
	gq->rx_bufs[gq->cur] = NULL;

This executes gq->rx_bufs[gq->cur] = NULL, discarding the pointer to the
memory previously allocated by netdev_alloc_frag(). Because the fragment
is neither attached to an SKB nor explicitly freed before the pointer is
zeroed, this appears to cause an unrecoverable memory leak.