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

From: Kalle Valo <[email-masked]>
Date: Wed, 15 Jun 2022 10:10:10 +0300

Toke Høiland-Jørgensen <[email-masked]> writes:

> 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]>

I'm wondering should these go to -rc or -next? Has anyone actually
tested these with real hardware? (syzbot testing does not count) With
the past bad experience with syzbot fixes I'm leaning towards -next to
have more time to fix any regressions.

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