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From:   Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= <toke@toke.dk>
To:     Pavel Skripkin <paskripkin@gmail.com>, kvalo@kernel.org,
        davem@davemloft.net, kuba@kernel.org
Cc:     linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Pavel Skripkin <paskripkin@gmail.com>,
        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: <d57bbedc857950659bfacac0ab48790c1eda00c8.1655145743.git.paskripkin@gmail.com>
References: <d57bbedc857950659bfacac0ab48790c1eda00c8.1655145743.git.paskripkin@gmail.com>
Date:   Tue, 14 Jun 2022 12:58:40 +0200
Message-ID: <87o7yvzf33.fsf@toke.dk>
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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=3D6ead44e37afb6866ac0c7dd121b4=
ce07cb665f60 [0]
> Link: https://syzkaller.appspot.com/bug?id=3Db8101ffcec107c0567a0cd8acbba=
cec91e9ee8de [1]
> Fixes: fb9987d0f748 ("ath9k_htc: Support for AR9271 chipset.")
> Reported-and-tested-by: syzbot+03110230a11411024147@syzkaller.appspotmail=
.com
> Reported-and-tested-by: syzbot+c6dde1f690b60e0b9fbe@syzkaller.appspotmail=
.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>