Re: [PATCH 2/5] net: renesas: rswitch: fix leaked pointer on error path

[Jacob Keller]

On 12/2/2024 5:49 AM, Nikita Yushchenko wrote:
> 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 32b32aa7e01f..3ad5858d3cdd 100644
> --- 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);
>  

Reviewed-by: Jacob Keller <jacob.e.keller@xxxxxxxxx>

>  err_kfree: