linux-kernel - Re: [GIT PULL 1/3] stm class: Fix a use-after-free

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Message-ID: <87a81nt84s.fsf@ashishki-desk.ger.corp.intel.com>
Date:   Fri, 22 Sep 2017 12:06:27 +0300
From:   Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To:     Greg KH <greg@...ah.com>
Cc:     Mathieu Poirier <mathieu.poirier@...aro.org>,
        Chunyan Zhang <zhang.chunyan@...aro.org>,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [GIT PULL 1/3] stm class: Fix a use-after-free

Greg KH <greg@...ah.com> writes:

> On Tue, Sep 19, 2017 at 06:47:40PM +0300, Alexander Shishkin wrote:
>> For reasons unknown, the stm_source removal path uses device_destroy()
>> to kill the underlying device object. Because device_destroy() uses
>> devt to look for the device to destroy and the fact that stm_source
>> devices don't have one (or all have the same one), it just picks the
>> first device in the class, which may well be the wrong one.
>> 
>> That is, loading stm_console and stm_heartbeat and then removing both
>> will die in dereferencing a freed object.
>> 
>> Since this should have been device_unregister() in the first place,
>> use it instead of device_destroy().
>> 
>> Signed-off-by: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
>> Fixes: 7bd1d4093c2 ("stm class: Introduce an abstraction for System Trace Module devices")
>> Cc: stable@...r.kernel.org
>> ---
>>  drivers/hwtracing/stm/core.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> Ugh, I just applied these as patches, and didn't do the git pull, sorry
> about that, my fault.

No worries, I'm fine either way.

> But really, patches for short series are really easy for me to do...

Sure, that's one reason why I sent it like that, so you get to choose.

Thanks,
--
Alex