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From:   Zheng Hacker <hackerzheng666@gmail.com>
Date:   Mon, 6 Nov 2023 13:16:26 +0800
Message-ID: <CAJedcCxoDVS-7jVwLvsWOWiv0aObyYBiG-GmqX4bq+Qp+i3iTw@mail.gmail.com>
Subject: Re: [PATCH v3] brcmfmac: Fix use-after-free bug in brcmf_cfg80211_detach
To:     Zheng Wang <zyytlz.wz@163.com>
Cc:     aspriel@gmail.com, franky.lin@broadcom.com,
        hante.meuleman@broadcom.com, kvalo@kernel.org,
        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,
        SHA-cyfmac-dev-list@infineon.com, linux-kernel@vger.kernel.org,
        security@kernel.org, stable@vger.kernel.org
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This is the candidate patch of CVE-2023-47233 :
https://nvd.nist.gov/vuln/detail/CVE-2023-47233

Appreciate the review and suggestions.

Zheng Wang <zyytlz.wz@163.com> =E4=BA=8E2023=E5=B9=B411=E6=9C=886=E6=97=A5=
=E5=91=A8=E4=B8=80 12:42=E5=86=99=E9=81=93=EF=BC=9A
>
> 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
> ---
> v3:
> - rename the subject as Johannes suggested
> v2:
> - fix the error of kernel test bot reported
> ---
>  drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c =
b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> index 667462369a32..646ec8bdf512 100644
> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> @@ -8431,6 +8431,9 @@ void brcmf_cfg80211_detach(struct brcmf_cfg80211_in=
fo *cfg)
>         if (!cfg)
>                 return;
>
> +       if (timer_pending(&cfg->escan_timeout))
> +               del_timer_sync(&cfg->escan_timeout);
> +       cancel_work_sync(&cfg->escan_timeout_work);
>         brcmf_pno_detach(cfg);
>         brcmf_btcoex_detach(cfg);
>         wiphy_unregister(cfg->wiphy);
> --
> 2.25.1
>