Re: mwifiex: Fix possible ABBA deadlock

[Kalle Valo]

Brian Norris <briannorris@xxxxxxxxxxxx> wrote:

> Quoting Jia-Ju Bai <baijiaju1990@xxxxxxxxx>:
> 
>   mwifiex_dequeue_tx_packet()
>      spin_lock_bh(&priv->wmm.ra_list_spinlock); --> Line 1432 (Lock A)
>      mwifiex_send_addba()
>        spin_lock_bh(&priv->sta_list_spinlock); --> Line 608 (Lock B)
> 
>   mwifiex_process_sta_tx_pause()
>      spin_lock_bh(&priv->sta_list_spinlock); --> Line 398 (Lock B)
>      mwifiex_update_ralist_tx_pause()
>        spin_lock_bh(&priv->wmm.ra_list_spinlock); --> Line 941 (Lock A)
> 
> Similar report for mwifiex_process_uap_tx_pause().
> 
> While the locking expectations in this driver are a bit unclear, the
> Fixed commit only intended to protect the sta_ptr, so we can drop the
> lock as soon as we're done with it.
> 
> IIUC, this deadlock cannot actually happen, because command event
> processing (which calls mwifiex_process_sta_tx_pause()) is
> sequentialized with TX packet processing (e.g.,
> mwifiex_dequeue_tx_packet()) via the main loop (mwifiex_main_process()).
> But it's good not to leave this potential issue lurking.
> 
> Fixes: f0f7c2275fb9 ("mwifiex: minor cleanups w/ sta_list_spinlock in cfg80211.c")
> Cc: Douglas Anderson <dianders@xxxxxxxxxxxx>
> Reported-by: TOTE Robot <oslab@xxxxxxxxxxxxxxx>
> Link: https://lore.kernel.org/linux-wireless/0e495b14-efbb-e0da-37bd-af6bd677ee2c@xxxxxxxxx/
> Signed-off-by: Brian Norris <briannorris@xxxxxxxxxxxx>
> Reviewed-by: Douglas Anderson <dianders@xxxxxxxxxxxx>

Patch applied to wireless-drivers-next.git, thanks.

1b8bb8919ef8 mwifiex: Fix possible ABBA deadlock

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/YaV0pllJ5p/EuUat@xxxxxxxxxx/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches