Re: [PATCH net-next v2] net: lan743x: fix potential out-of-bounds write in lan743x_ptp_io_event_clock_get()

[<Rengarajan.S@microchip.com>]

Hi Alexey,

On Mon, 2025-06-16 at 11:37 +0000, Alexey Kodanev wrote:
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> 
> Before calling lan743x_ptp_io_event_clock_get(), the 'channel' value
> is checked against the maximum value of
> PCI11X1X_PTP_IO_MAX_CHANNELS(8).
> This seems correct and aligns with the PTP interrupt status register
> (PTP_INT_STS) specifications.
> 
> However, lan743x_ptp_io_event_clock_get() writes to ptp->extts[] with
> only LAN743X_PTP_N_EXTTS(4) elements, using channel as an index:
> 
>     lan743x_ptp_io_event_clock_get(..., u8 channel,...)
>     {
>         ...
>         /* Update Local timestamp */
>         extts = &ptp->extts[channel];
>         extts->ts.tv_sec = sec;
>         ...
>     }
> 
> To avoid an out-of-bounds write and utilize all the supported GPIO
> inputs, set LAN743X_PTP_N_EXTTS to 8.
> 
> Detected using the static analysis tool - Svace.
> Fixes: 60942c397af6 ("net: lan743x: Add support for PTP-IO Event
> Input External Timestamp (extts)")
> Signed-off-by: Alexey Kodanev <aleksei.kodanev@bell-sw.com>
> ---
> 
> v2: Increase LAN743X_PTP_N_EXTTS to 8
> 
>  drivers/net/ethernet/microchip/lan743x_ptp.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/microchip/lan743x_ptp.h
> b/drivers/net/ethernet/microchip/lan743x_ptp.h
> index e8d073bfa2ca..f33dc83c5700 100644
> --- a/drivers/net/ethernet/microchip/lan743x_ptp.h
> +++ b/drivers/net/ethernet/microchip/lan743x_ptp.h
> @@ -18,9 +18,9 @@
>   */
>  #define LAN743X_PTP_N_EVENT_CHAN       2
>  #define LAN743X_PTP_N_PEROUT           LAN743X_PTP_N_EVENT_CHAN
> -#define LAN743X_PTP_N_EXTTS            4
> -#define LAN743X_PTP_N_PPS              0
>  #define PCI11X1X_PTP_IO_MAX_CHANNELS   8
> +#define LAN743X_PTP_N_EXTTS            PCI11X1X_PTP_IO_MAX_CHANNELS
> +#define LAN743X_PTP_N_PPS              0
>  #define PTP_CMD_CTL_TIMEOUT_CNT                50

Thanks for the update. Changing the LAN743X_PTP_N_EXTTS from 4 to 8
looks valid here.

> 
>  struct lan743x_adapter;
> --
> 2.25.1
> 

Acked-by: Rengarajan S <rengarajan.s@microchip.com>