Re: [PATCH] Fix a double free bug in rsi_91x_deinit

From: Guenter Roeck <linux@roeck-us.net>
To: Hui Peng <benquike@gmail.com>
Cc: security@kernel.org, Mathias Payer <mathias.payer@nebelwelt.net>,
	Kalle Valo <kvalo@codeaurora.org>,
	"David S. Miller" <davem@davemloft.net>,
	linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Fix a double free bug in rsi_91x_deinit
Date: Sat, 31 Aug 2019 11:18:52 -0700	[thread overview]
Message-ID: <20190831181852.GA22160@roeck-us.net> (raw)
In-Reply-To: <20190819220230.10597-1-benquike@gmail.com>

On Mon, Aug 19, 2019 at 06:02:29PM -0400, Hui Peng wrote:
> `dev` (struct rsi_91x_usbdev *) field of adapter
> (struct rsi_91x_usbdev *) is allocated  and initialized in
> `rsi_init_usb_interface`. If any error is detected in information
> read from the device side,  `rsi_init_usb_interface` will be
> freed. However, in the higher level error handling code in
> `rsi_probe`, if error is detected, `rsi_91x_deinit` is called
> again, in which `dev` will be freed again, resulting double free.
> 
> This patch fixes the double free by removing the free operation on
> `dev` in `rsi_init_usb_interface`, because `rsi_91x_deinit` is also
> used in `rsi_disconnect`, in that code path, the `dev` field is not
>  (and thus needs to be) freed.
> 
> This bug was found in v4.19, but is also present in the latest version
> of kernel.
> 
> Reported-by: Hui Peng <benquike@gmail.com>
> Reported-by: Mathias Payer <mathias.payer@nebelwelt.net>
> Signed-off-by: Hui Peng <benquike@gmail.com>

FWIW:

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

This patch is listed as fix for CVE-2019-15504, which has a CVSS 2.0 score
of 10.0 (high) and CVSS 3.0 score of 9.8 (critical).

Are there any plans to apply this patch to the upstream kernel anytime
soon ? If not, are there reasons to believe that the problem is not as
severe as its CVSS score may indicate ?

Thanks,
Guenter

> ---
>  drivers/net/wireless/rsi/rsi_91x_usb.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/rsi/rsi_91x_usb.c b/drivers/net/wireless/rsi/rsi_91x_usb.c
> index c0a163e40402..ac917227f708 100644
> --- a/drivers/net/wireless/rsi/rsi_91x_usb.c
> +++ b/drivers/net/wireless/rsi/rsi_91x_usb.c
> @@ -640,7 +640,6 @@ static int rsi_init_usb_interface(struct rsi_hw *adapter,
>  	kfree(rsi_dev->tx_buffer);
>  
>  fail_eps:
> -	kfree(rsi_dev);
>  
>  	return status;
>  }
> -- 
> 2.22.1
> 