Re: [PATCH net v2] net: ravb: fix use-after-free in ravb_get_ts_info

["Niklas Söderlund" <niklas.soderlund@ragnatech.se>]

Hi Xuanqiang,

On 2026-08-02 17:07:50 +0800, Xuanqiang Luo wrote:
> From: Xuanqiang Luo <luoxuanqiang@kylinos.cn>
> 
> The PHC is registered by ravb_open() and unregistered by ravb_close().
> However, ravb_ptp_stop() leaves priv->ptp.clock pointing at the freed
> clock. Since the netdev remains registered after ndo_stop, get_ts_info
> can still pass the dangling pointer to ptp_clock_index(), resulting in a
> use-after-free.
> 
> Clear the pointer after unregistering the clock and only advertise hardware
> timestamping support when a PHC is available.
> 
> Fixes: a0d2f20650e8 ("Renesas Ethernet AVB PTP clock driver")
> Cc: stable@vger.kernel.org
> Signed-off-by: Xuanqiang Luo <luoxuanqiang@kylinos.cn>

Thanks for re spinning this,

Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>

> ---
> v2:
> - Only advertise hardware timestamping support when a PHC is available
>   (Niklas Söderlund).
> 
> v1: https://lore.kernel.org/all/20260731063254.71260-1-xuanqiang.luo@linux.dev/
> 
>  drivers/net/ethernet/renesas/ravb_main.c | 2 +-
>  drivers/net/ethernet/renesas/ravb_ptp.c  | 5 ++++-
>  2 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
> index 5f88733094d0..f22cff05ba35 100644
> --- a/drivers/net/ethernet/renesas/ravb_main.c
> +++ b/drivers/net/ethernet/renesas/ravb_main.c
> @@ -1768,7 +1768,7 @@ static int ravb_get_ts_info(struct net_device *ndev,
>  	struct ravb_private *priv = netdev_priv(ndev);
>  	const struct ravb_hw_info *hw_info = priv->info;
>  
> -	if (hw_info->gptp || hw_info->ccc_gac) {
> +	if ((hw_info->gptp || hw_info->ccc_gac) && priv->ptp.clock) {
>  		info->so_timestamping =
>  			SOF_TIMESTAMPING_TX_SOFTWARE |
>  			SOF_TIMESTAMPING_TX_HARDWARE |
> diff --git a/drivers/net/ethernet/renesas/ravb_ptp.c b/drivers/net/ethernet/renesas/ravb_ptp.c
> index 226c6c0ab945..fc8c601ed3a5 100644
> --- a/drivers/net/ethernet/renesas/ravb_ptp.c
> +++ b/drivers/net/ethernet/renesas/ravb_ptp.c
> @@ -337,5 +337,8 @@ void ravb_ptp_stop(struct net_device *ndev)
>  	ravb_write(ndev, 0, GIC);
>  	ravb_write(ndev, 0, GIS);
>  
> -	ptp_clock_unregister(priv->ptp.clock);
> +	if (priv->ptp.clock) {
> +		ptp_clock_unregister(priv->ptp.clock);
> +		priv->ptp.clock = NULL;
> +	}
>  }
> -- 
> 2.51.0
> 

-- 
Kind Regards,
Niklas Söderlund