linux-kernel - Re: [PATCH net-next V2] ptp: fix corrupted list in ptp

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Message-ID: <ZUWpRBdv76P_H8aV@hoboy.vegasvil.org>
Date:   Fri, 3 Nov 2023 19:15:32 -0700
From:   Richard Cochran <richardcochran@...il.com>
To:     Jeremy Cline <jeremy@...ine.org>
Cc:     Edward Adam Davis <eadavis@...com>, habetsm.xilinx@...il.com,
        davem@...emloft.net, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, reibax@...il.com,
        syzbot+df3f3ef31f60781fa911@...kaller.appspotmail.com,
        syzkaller-bugs@...glegroups.com
Subject: Re: [PATCH net-next V2] ptp: fix corrupted list in ptp_open

On Fri, Nov 03, 2023 at 07:13:31PM -0700, Richard Cochran wrote:
> See ptp_clock.c:
> 
>  416         case PTP_CLOCK_EXTTS:
>  417                 /* Enqueue timestamp on selected queues */
>  418                 list_for_each_entry(tsevq, &ptp->tsevqs, qlist) {
>  419                         if (test_bit((unsigned int)event->index, tsevq->mask))
>  420                                 enqueue_external_timestamp(tsevq, event);
>  421                 }
>  422                 wake_up_interruptible(&ptp->tsev_wq);
>  423                 break;

And that code can be called from interrupt context.

Thus the mutex won't work.

It needs to be a spin lock instead.

Thanks,
Richard