Sender: Larry Finger <larry.finger@gmail.com>
Message-ID: <26b9ce8e-a100-399d-58d0-0a649380f8cb@lwfinger.net>
Date:   Fri, 17 Mar 2023 13:32:17 -0500
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Subject: Re: rtw88: kernel NULL pointer dereference
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To:     Tim K <tpkuester@gmail.com>, linux-wireless@vger.kernel.org
References: <CA+shoWQ7P49jhQasofDcTdQhiuarPTjYEDa--NiVVx494WcuQw@mail.gmail.com>
From:   Larry Finger <Larry.Finger@lwfinger.net>
In-Reply-To: <CA+shoWQ7P49jhQasofDcTdQhiuarPTjYEDa--NiVVx494WcuQw@mail.gmail.com>
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On 3/17/23 13:12, Tim K wrote:
> Hello again all,
> 
> I've been running a few rtw8822bu dongles in monitor mode doing a
> packet capture on an STM32, running Linux 5.15. It's been fairly
> stable over a few days, but I checked back in on it and found this in
> the log.
> 
> Any thoughts on what could have caused this? This is from lwfinger's
> GitHub repo at 4bede29 (I believe.)
> 
> [406207.728602] 8<--- cut here ---
> [406207.730533] Unable to handle kernel NULL pointer dereference at
> virtual address 00000004
> [406207.740137] pgd = 40e434d7
> [406207.741665] [00000004] *pgd=00000000
> [406207.745300] Internal error: Oops: 5 [#1] PREEMPT SMP ARM
> [406207.801313] CPU: 0 PID: 23145 Comm: kworker/u4:2 Tainted: G
>     O      5.15.24 #13
> [406207.809516] Hardware name: STM32 (Device Tree Support)
> [406207.814783] Workqueue: rtw88_usb: rx wq rtw_usb_rx_handler [rtw88_usb]
> [406207.821397] PC is at rtw_rx_fill_rx_status+0x40/0x278 [rtw_core]
> [406207.827604] LR is at rtw_rx_fill_rx_status+0x3c/0x278 [rtw_core]
> [406207.833666] pc : [<bf324cac>]    lr : [<bf324ca8>]    psr: 400f0113
> [406207.840043] sp : c5379e20  ip : c5379eb8  fp : 00000001
> ...
> [406208.084918] [<bf324cac>] (rtw_rx_fill_rx_status [rtw_core]) from
> [<bf3c6b44>] (rtw8822b_query_rx_desc+0x10c/0x19c [rtw_8822b])
> [406208.096524] [<bf3c6b44>] (rtw8822b_query_rx_desc [rtw_8822b]) from
> [<bf416920>] (rtw_usb_rx_handler+0x6c/0x16c [rtw88_usb])
> [406208.107820] [<bf416920>] (rtw_usb_rx_handler [rtw88_usb]) from
> [<c01455cc>] (process_one_work+0x1dc/0x588)
> [406208.117570] [<c01455cc>] (process_one_work) from [<c0145e04>]
> (worker_thread+0x5c/0x568)
> [406208.125790] [<c0145e04>] (worker_thread) from [<c014c230>]
> (kthread+0x144/0x160)
> [406208.133310] [<c014c230>] (kthread) from [<c0100130>]
> (ret_from_fork+0x14/0x24)
> ...
> [406208.186520] ---[ end trace 140c234232a74c11 ]---

Tim,

I can tell from your dump that you are not running x86_64 hardware. Is it ARM?

In any case, please run the command 'gdb rtw_core.ko' while in the rtw88 
directory, and once gdb gets started, enter the command
l *rtw_rx_fill_rx_status+0x40

Report the output. That will show the line of code that is failing. We should be 
able to figure it out from there.

Larry