Re: [PATCH] hippi: fix possible buffer overflow caused by bad DMA value in rr_start_xmit()

[Paolo Abeni]

On Wed, 2024-06-12 at 17:31 +0800, Huai-Yuan Liu wrote:
> The value rrpriv->info->tx_ctrl is stored in DMA memory, and it is
> assigned to txctrl, so txctrl->pi can be modified at any time by malicious
> hardware. Becausetxctrl->pi is assigned to index, buffer overflow may
> occur when the code "rrpriv->tx_skbuff[index]" is executed.
> 
> To address this issue, the index should be checked.
> 
> Fixes: f33a7251c825 ("hippi: switch from 'pci_' to 'dma_' API")
> Signed-off-by: Huai-Yuan Liu <qq810974084@xxxxxxxxx>
> ---
>  drivers/net/hippi/rrunner.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/net/hippi/rrunner.c b/drivers/net/hippi/rrunner.c
> index aa8f828a0ae7..184f0933bca0 100644
> --- a/drivers/net/hippi/rrunner.c
> +++ b/drivers/net/hippi/rrunner.c
> @@ -1440,6 +1440,11 @@ static netdev_tx_t rr_start_xmit(struct sk_buff *skb,
>  	txctrl = &rrpriv->info->tx_ctrl;
>  
>  	index = txctrl->pi;
> +	if (index < 0 || index >= TX_RING_ENTRIES) {

'index' is u32, the first condition is not needed.

> +		printk("invalid index value %02x\n", index);

please use netdev_err() instead.

Thanks,

Paolo