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 Paolo,

On Thu, 2025-06-19 at 12:04 +0200, Paolo Abeni wrote:
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> 
> On 6/16/25 1:37 PM, Alexey Kodanev wrote:
> > 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>
> 
> @Rengarajan: I see you suggested this approach on V1, but it would be
> nice to have explicit ack here (or even better in this case tested-
> by)

Yes, I agree with the recent change made by Alexey to set
LAN743X_PTP_N_EXTTS to 8. I have tested this on my end using GPIO
numbers greater than 4 and did not encounter any issues. I will go
ahead and provide my acknowledgment for Alexey's patch.

Thanks,
Rengarajan S

> 
> Thanks,
> 
> Paolo
>