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From:   Kalle Valo <kvalo@kernel.org>
To:     Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= <toke@toke.dk>
Cc:     Pavel Skripkin <paskripkin@gmail.com>, davem@davemloft.net,
        kuba@kernel.org, linux-wireless@vger.kernel.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        syzbot+03110230a11411024147@syzkaller.appspotmail.com,
        syzbot+c6dde1f690b60e0b9fbe@syzkaller.appspotmail.com
Subject: Re: [PATCH v6 1/2] ath9k: fix use-after-free in ath9k_hif_usb_rx_cb
In-Reply-To: <87o7yvzf33.fsf@toke.dk> ("Toke \=\?utf-8\?Q\?H\=C3\=B8iland-J\?\=
 \=\?utf-8\?Q\?\=C3\=B8rgensen\=22's\?\= message of
        "Tue, 14 Jun 2022 12:58:40 +0200")
References: <d57bbedc857950659bfacac0ab48790c1eda00c8.1655145743.git.paskripkin@gmail.com>
        <87o7yvzf33.fsf@toke.dk>
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Date:   Wed, 15 Jun 2022 10:10:10 +0300
Message-ID: <87k09ipfl9.fsf@kernel.org>
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Toke H=C3=B8iland-J=C3=B8rgensen <toke@toke.dk> writes:

> Pavel Skripkin <paskripkin@gmail.com> 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 =3D 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=3D6ead44e37afb6866ac0c7dd121b=
4ce07cb665f60 [0]
>> Link: https://syzkaller.appspot.com/bug?id=3Db8101ffcec107c0567a0cd8acbb=
acec91e9ee8de [1]
>> Fixes: fb9987d0f748 ("ath9k_htc: Support for AR9271 chipset.")
>> Reported-and-tested-by: syzbot+03110230a11411024147@syzkaller.appspotmai=
l.com
>> Reported-and-tested-by: syzbot+c6dde1f690b60e0b9fbe@syzkaller.appspotmai=
l.com
>> Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
>
> 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 H=C3=B8iland-J=C3=B8rgensen <toke@toke.dk>

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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