linux-kernel - Re: [PATCH v5] wifi: brcmfmac: Fix use-after-free bug in brcmf_cfg80211

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Date:   Thu, 16 Nov 2023 20:02:06 +0100
From:   Arend Van Spriel <arend.vanspriel@...adcom.com>
To:     Takashi Iwai <tiwai@...e.de>
CC:     Zheng Hacker <hackerzheng666@...il.com>,
        Kalle Valo <kvalo@...nel.org>, Zheng Wang <zyytlz.wz@....com>,
        <aspriel@...il.com>, <franky.lin@...adcom.com>,
        <hante.meuleman@...adcom.com>, <johannes.berg@...el.com>,
        <marcan@...can.st>, <linus.walleij@...aro.org>,
        <jisoo.jang@...sei.ac.kr>, <linuxlovemin@...sei.ac.kr>,
        <wataru.gohda@...ress.com>, <linux-wireless@...r.kernel.org>,
        <brcm80211-dev-list.pdl@...adcom.com>,
        <SHA-cyfmac-dev-list@...ineon.com>, <linux-kernel@...r.kernel.org>,
        <security@...nel.org>, <stable@...r.kernel.org>
Subject: Re: [PATCH v5] wifi: brcmfmac: Fix use-after-free bug in brcmf_cfg80211_detach

On November 16, 2023 7:25:16 PM Takashi Iwai <tiwai@...e.de> wrote:

> On Thu, 16 Nov 2023 19:20:06 +0100,
> Arend Van Spriel wrote:
>>
>> On November 15, 2023 4:00:46 PM Zheng Hacker <hackerzheng666@...il.com> wrote:
>>
>>> Arend van Spriel <arend.vanspriel@...adcom.com> 于2023年11月13日周一 17:18写道：
>>>>
>>>> On November 8, 2023 4:03:26 AM Zheng Hacker <hackerzheng666@...il.com>
>>>> wrote:
>>>>
>>>>> Arend Van Spriel <arend.vanspriel@...adcom.com> 于2023年11月6日周一 23:48写道：
>>>>>>
>>>>>> On November 6, 2023 3:44:53 PM Zheng Hacker <hackerzheng666@...il.com> wrote:
>>>>>>
>>>>>>> Thanks! I didn't test it for I don't have a device. Very appreciated
>>>>>>> if anyone could help with that.
>>>>>>
>>>>>> I would volunteer, but it made me dig deep and not sure if there is a
>>>>>> problem to solve here.
>>>>>>
>>>>>> brcmf_cfg80211_detach() calls wl_deinit_priv() -> brcmf_abort_scanning() ->
>>>>>> brcmf_notify_escan_complete() which does delete the timer.
>>>>>>
>>>>>> What am I missing here?
>>>>>
>>>>> Thanks four your detailed review. I did see the code and not sure if
>>>>> brcmf_notify_escan_complete
>>>>> would be triggered for sure. So in the first version I want to delete
>>>>> the pending timer ahead of time.
>>>>
>>>> Why requesting a CVE when you are not sure? Seems a bit hasty to put it
>>>> mildly.
>>>
>>> I'm sure the issue exists because there's only cancler of timer but not woker.
>>> As there's similar CVEs before like : https://github.com/V4bel/CVE-2022-41218,
>>> I submit it as soon as I found it.
>>
>> Ah, yes. The cancel_work_sync() can also be done in
>> brcmf_notify_escan_complete().
>
> AFAIUC, brcmf_notify_scan_complete() is called from the work itself,
> too, hence you can't issue cancel_work_sync() there (unless you make
> it conditional).

Hi Takashi,

You are obviously right. Let's wait and see what v6 will look like ;-)

Regards,
Arend



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