Re: [PATCH v5] wifi: brcmfmac: Fix use-after-free bug in brcmf_cfg80211_detach

[Arend Van Spriel]

On November 6, 2023 3:44:53 PM Zheng Hacker <hackerzheng666@xxxxxxxxx> 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?

Regards,
Arend

> Kalle Valo <kvalo@xxxxxxxxxx> 于2023年11月6日周一 22:41写道：
> > Zheng Wang <zyytlz.wz@xxxxxxx> 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@xxxxxxx>
> > > Cc: stable@xxxxxxxxxxxxxxx
> > > ---
> > > 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@xxxxxxx/
> >
> > --
> > https://patchwork.kernel.org/project/linux-wireless/list/
> >
> > https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

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