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

From: Hui Peng <benquike@gmail.com>
To: Guenter Roeck <linux@roeck-us.net>
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 14:32:57 -0400	[thread overview]
Message-ID: <d5b3e9ff-ddca-52fc-81cf-9a213ad2c251@gmail.com> (raw)
In-Reply-To: <20190831181852.GA22160@roeck-us.net>

On 8/31/19 2:18 PM, Guenter Roeck wrote:
> 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 ?
This patch is also still under review.
> 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
>>