Re: [PATCH v4] wifi: brcmfmac: Fix use-after-free bug in brcmf_cfg80211_detach

[Arend van Spriel]

On 11/6/2023 8:30 AM, Zheng Wang wrote:
> This is the candidate patch of CVE-2023-47233 :
> https://nvd.nist.gov/vuln/detail/CVE-2023-47233

[...]

> Fix it by deleting the timer and canceling the worker in
> brcmf_cfg80211_detach.
>
> Fixes: e756af5b30b0 ("brcmfmac: add e-scan support.")
Reviewed-by: Arend van Spriel <arend.vanspriel@xxxxxxxxxxxx>
> Signed-off-by: Zheng Wang <zyytlz.wz@xxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
> 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 | 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_info *cfg)
>   	if (!cfg)
>   		return;
>   
> +	if (timer_pending(&cfg->escan_timeout))
> +		del_timer_sync(&cfg->escan_timeout);

del_timer_sync() is kept for legacy. Use timer_delete_sync() instead 
[1]. Also checking timer_pending() before deletion is useless looking at 
the return values from timer_delete_sync():

 * Return:
 * * %0	- The timer was not pending
 * * %1	- The timer was pending and deactivated

[1] 
https://elixir.bootlin.com/linux/latest/source/include/linux/timer.h#L190
> +	cancel_work_sync(&cfg->escan_timeout_work);
>   	brcmf_pno_detach(cfg);
>   	brcmf_btcoex_detach(cfg);
>   	wiphy_unregister(cfg->wiphy);

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