Subject: Re: [PATCH v6 1/2] ath9k: fix use-after-free in ath9k_hif_usb_rx_cb

From: Toke Høiland-Jørgensen <[email-masked]>
Date: Tue, 14 Jun 2022 12:58:40 +0200

Pavel Skripkin <[email-masked]> writes:

> Syzbot reported use-after-free Read in ath9k_hif_usb_rx_cb() [0]. The
> problem was in incorrect htc_handle->drv_priv initialization.
>
> Probable call trace which can trigger use-after-free:
>
> ath9k_htc_probe_device()
>   /* htc_handle->drv_priv = priv; */
>   ath9k_htc_wait_for_target()      <--- Failed
>   ieee80211_free_hw()		   <--- priv pointer is freed
>
> <IRQ>
> ...
> ath9k_hif_usb_rx_cb()
>   ath9k_hif_usb_rx_stream()
>    RX_STAT_INC()		<--- htc_handle->drv_priv access
>
> In order to not add fancy protection for drv_priv we can move
> htc_handle->drv_priv initialization at the end of the
> ath9k_htc_probe_device() and add helper macro to make
> all *_STAT_* macros NULL safe, since syzbot has reported related NULL
> deref in that macros [1]
>
> Link: https://syzkaller.appspot.com/bug?id=6ead44e37afb6866ac0c7dd121b4ce07cb665f60 [0]
> Link: https://syzkaller.appspot.com/bug?id=b8101ffcec107c0567a0cd8acbbacec91e9ee8de [1]
> Fixes: fb9987d0f748 ("ath9k_htc: Support for AR9271 chipset.")
> Reported-and-tested-by: [email-masked]
> Reported-and-tested-by: [email-masked]
> Signed-off-by: Pavel Skripkin <[email-masked]>

Alright, since we've heard no more objections and the status quo is
definitely broken, let's get this merged and we can follow up with any
other fixes as necessary...

Acked-by: Toke Høiland-Jørgensen <[email-masked]>