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Date:   Tue, 4 Apr 2023 11:44:35 -0500
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Subject: Re: rtw88: kernel NULL pointer dereference
To:     Tim K <tpkuester@gmail.com>
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On 4/4/23 10:07, Tim K wrote:
>> As rx_status is local to the routine, the error has to be in the right-hand side
>> of the statement. As hw->conf.....->center_freq is apparently OK most of the
>> time, I think you are getting a spurious RX interrupt. I have pushed a patch
>> that will show if hw is NULL, and quit the routine. Do a 'git pull', make... and
>> let me know what you see in the log.
> 
> Updated the drivers to e6d63e1 on your github repo, and ran for about
> 16 hours happily. Came back this morning to an error. I've attached
> the stack trace, and the line of code that caused the error.
> 
>>>> l *rtw_rx_fill_rx_status+0x48
> 0x8cd8 is in rtw_rx_fill_rx_status (/home/tkuester/code/rtw88/rx.c:163).
> 163        rx_status->freq = hw->conf.chandef.chan->center_freq;
> 
> Much to my chagrin, it seems I have an intermittent USB cable causing
> spurious disconnects. However, while this does appear to be associated
> with the issue, I also discovered this issue 20-some odd seconds into
> boot on one boot cycle with no mention of USB disconnects.

Tim,

I suspect that your intermittent USB cable could also produce spurious 
interrupts, which I thought might be the cause of the problem.

I had done some updates against wireless-next yesterday. To them, I added an 
additional check in this routine. The driver should survive things like bad 
cables without crashing the kernel. Do a pull, and let me know what you learn. I 
would appreciate learning what happens with the faulty cable.

Larry