linux-kernel - Re: [PATCH] Fix a double free bug in rsi_91x

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Date:   Sun, 01 Sep 2019 11:03:36 +0300
From:   Kalle Valo <kvalo@...eaurora.org>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Hui Peng <benquike@...il.com>, security@...nel.org,
        Mathias Payer <mathias.payer@...elwelt.net>,
        "David S. Miller" <davem@...emloft.net>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Fix a double free bug in rsi_91x_deinit

Guenter Roeck <linux@...ck-us.net> writes:

> 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@...il.com>
>> Reported-by: Mathias Payer <mathias.payer@...elwelt.net>
>> Signed-off-by: Hui Peng <benquike@...il.com>
>
> FWIW:
>
> Reviewed-by: Guenter Roeck <linux@...ck-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).

A double free in error path is considered as a critical CVE issue? I'm
very curious, why is that?

> Are there any plans to apply this patch to the upstream kernel anytime
> soon ?

I was on vacation last week and hence I have not been able to apply any
wireless patches. I should be able to catch up next week.

-- 
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches