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

[Paolo Abeni <pabeni@redhat.com>]

On 6/19/25 12:39 PM, Rengarajan.S@microchip.com wrote:
> On Mon, 2025-06-16 at 11:37 +0000, Alexey Kodanev wrote:
>> EXTERNAL EMAIL: Do not click links or open attachments unless you
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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>

Thanks!

FTR, I'm applying this patch to the 'net' tree as the issue is present
there since a while and the change itself does not fit net-next IMHO.

/P