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From:   Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= <toke@toke.dk>
To:     Fedor Pchelkin <pchelkin@ispras.ru>, Kalle Valo <kvalo@kernel.org>
Cc:     Fedor Pchelkin <pchelkin@ispras.ru>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Sujith <Sujith.Manoharan@atheros.com>,
        "John W. Linville" <linville@tuxdriver.com>,
        Vasanthakumar Thiagarajan <vasanth@atheros.com>,
        Senthil Balasubramanian <senthilkumar@atheros.com>,
        linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Alexey Khoroshilov <khoroshilov@ispras.ru>,
        lvc-project@linuxtesting.org,
        syzbot+e008dccab31bd3647609@syzkaller.appspotmail.com,
        syzbot+6692c72009680f7c4eb2@syzkaller.appspotmail.com
Subject: Re: [PATCH v2] wifi: ath9k: htc_hst: free skb in ath9k_htc_rx_msg()
 if there is no callback function
In-Reply-To: <20230103143202.274163-1-pchelkin@ispras.ru>
References: <20230103143202.274163-1-pchelkin@ispras.ru>
Date:   Tue, 03 Jan 2023 22:04:31 +0100
Message-ID: <87358r49eo.fsf@toke.dk>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

Fedor Pchelkin <pchelkin@ispras.ru> writes:

> It is stated that ath9k_htc_rx_msg() either frees the provided skb or
> passes its management to another callback function. However, the skb is
> not freed in case there is no another callback function, and Syzkaller was
> able to cause a memory leak. Also minor comment fix.
>
> Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
>
> Fixes: fb9987d0f748 ("ath9k_htc: Support for AR9271 chipset.")
> Reported-by: syzbot+e008dccab31bd3647609@syzkaller.appspotmail.com
> Reported-by: syzbot+6692c72009680f7c4eb2@syzkaller.appspotmail.com
> Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
> Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
> ---
> v1->v2: added Reported-by tag
>
>  drivers/net/wireless/ath/ath9k/htc_hst.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/wireless/ath/ath9k/htc_hst.c b/drivers/net/wireless/ath/ath9k/htc_hst.c
> index ca05b07a45e6..7d5041eb5f29 100644
> --- a/drivers/net/wireless/ath/ath9k/htc_hst.c
> +++ b/drivers/net/wireless/ath/ath9k/htc_hst.c
> @@ -391,7 +391,7 @@ static void ath9k_htc_fw_panic_report(struct htc_target *htc_handle,
>   * HTC Messages are handled directly here and the obtained SKB
>   * is freed.
>   *
> - * Service messages (Data, WMI) passed to the corresponding
> + * Service messages (Data, WMI) are passed to the corresponding
>   * endpoint RX handlers, which have to free the SKB.
>   */
>  void ath9k_htc_rx_msg(struct htc_target *htc_handle,
> @@ -478,6 +478,8 @@ void ath9k_htc_rx_msg(struct htc_target *htc_handle,
>  		if (endpoint->ep_callbacks.rx)
>  			endpoint->ep_callbacks.rx(endpoint->ep_callbacks.priv,
>  						  skb, epid);
> +		else
> +			kfree_skb(skb);

Shouldn't this be 'goto invalid' like all the other error paths in that
function?

-Toke