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References: <20231106141704.866455-1-zyytlz.wz@163.com> <87o7g7ueom.fsf@kernel.org>
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From:   Zheng Hacker <hackerzheng666@gmail.com>
Date:   Mon, 6 Nov 2023 22:44:41 +0800
Message-ID: <CAJedcCytuGmvubqbSZgsU3Db=rg=xM+kSuLZn8BSvA18Yn+9Jw@mail.gmail.com>
Subject: Re: [PATCH v5] wifi: brcmfmac: Fix use-after-free bug in brcmf_cfg80211_detach
To:     Kalle Valo <kvalo@kernel.org>
Cc:     Zheng Wang <zyytlz.wz@163.com>, aspriel@gmail.com,
        franky.lin@broadcom.com, hante.meuleman@broadcom.com,
        johannes.berg@intel.com, marcan@marcan.st,
        linus.walleij@linaro.org, jisoo.jang@yonsei.ac.kr,
        linuxlovemin@yonsei.ac.kr, wataru.gohda@cypress.com,
        linux-wireless@vger.kernel.org,
        brcm80211-dev-list.pdl@broadcom.com, arend.vanspriel@broadcom.com,
        SHA-cyfmac-dev-list@infineon.com, linux-kernel@vger.kernel.org,
        security@kernel.org, stable@vger.kernel.org
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Thanks! I didn't test it for I don't have a device. Very appreciated
if anyone could help with that.

Kalle Valo <kvalo@kernel.org> =E4=BA=8E2023=E5=B9=B411=E6=9C=886=E6=97=A5=
=E5=91=A8=E4=B8=80 22:41=E5=86=99=E9=81=93=EF=BC=9A
>
> Zheng Wang <zyytlz.wz@163.com> writes:
>
> > This is the candidate patch of CVE-2023-47233 :
> > https://nvd.nist.gov/vuln/detail/CVE-2023-47233
> >
> > In brcm80211 driver,it starts with the following invoking chain
> > to start init a timeout worker:
> >
> > ->brcmf_usb_probe
> >   ->brcmf_usb_probe_cb
> >     ->brcmf_attach
> >       ->brcmf_bus_started
> >         ->brcmf_cfg80211_attach
> >           ->wl_init_priv
> >             ->brcmf_init_escan
> >               ->INIT_WORK(&cfg->escan_timeout_work,
> >                 brcmf_cfg80211_escan_timeout_worker);
> >
> > If we disconnect the USB by hotplug, it will call
> > brcmf_usb_disconnect to make cleanup. The invoking chain is :
> >
> > brcmf_usb_disconnect
> >   ->brcmf_usb_disconnect_cb
> >     ->brcmf_detach
> >       ->brcmf_cfg80211_detach
> >         ->kfree(cfg);
> >
> > While the timeout woker may still be running. This will cause
> > a use-after-free bug on cfg in brcmf_cfg80211_escan_timeout_worker.
> >
> > Fix it by deleting the timer and canceling the worker in
> > brcmf_cfg80211_detach.
> >
> > Fixes: e756af5b30b0 ("brcmfmac: add e-scan support.")
> > Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
> > Cc: stable@vger.kernel.org
> > ---
> > v5:
> > - replace del_timer_sync with timer_shutdown_sync suggested by
> > Arend and Takashi
> > v4:
> > - rename the subject and add CVE number as Ping-Ke Shih suggested
> > v3:
> > - rename the subject as Johannes suggested
> > v2:
> > - fix the error of kernel test bot reported
> > ---
> >  drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.=
c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> > index 667462369a32..a8723a61c9e4 100644
> > --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> > +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> > @@ -8431,6 +8431,8 @@ void brcmf_cfg80211_detach(struct brcmf_cfg80211_=
info *cfg)
> >       if (!cfg)
> >               return;
> >
> > +     timer_shutdown_sync(&cfg->escan_timeout);
> > +     cancel_work_sync(&cfg->escan_timeout_work);
> >       brcmf_pno_detach(cfg);
> >       brcmf_btcoex_detach(cfg);
> >       wiphy_unregister(cfg->wiphy);
>
> Has anyone tested this on a real device? As v1 didn't even compile I am
> very cautious:
>
> https://patchwork.kernel.org/project/linux-wireless/patch/20231104054709.=
716585-1-zyytlz.wz@163.com/
>
> --
> https://patchwork.kernel.org/project/linux-wireless/list/
>
> https://wireless.wiki.kernel.org/en/developers/documentation/submittingpa=
tches