linux-kernel - Re: [PATCH v3] media: mxl111sf: change mutex

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Message-ID: <c1c0d250-afa1-254e-421a-d35790688c60@gmail.com>
Date:   Sun, 12 Sep 2021 18:49:52 +0300
From:   Pavel Skripkin <paskripkin@...il.com>
To:     mkrufky@...uxtv.org, mchehab@...nel.org, crope@....fi,
        sean@...s.org
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        syzbot+5ca0bf339f13c4243001@...kaller.appspotmail.com
Subject: Re: [PATCH v3] media: mxl111sf: change mutex_init() location

On 8/19/21 13:42, Pavel Skripkin wrote:
> Syzbot reported, that mxl111sf_ctrl_msg() uses uninitialized
> mutex. The problem was in wrong mutex_init() location.
> 
> Previous mutex_init(&state->msg_lock) call was in ->init() function, but
> dvb_usbv2_init() has this order of calls:
> 
> 	dvb_usbv2_init()
> 	  dvb_usbv2_adapter_init()
> 	    dvb_usbv2_adapter_frontend_init()
> 	      props->frontend_attach()
> 
> 	  props->init()
> 
> Since mxl111sf_* devices call mxl111sf_ctrl_msg() in ->frontend_attach()
> internally we need to initialize state->msg_lock before
> frontend_attach(). To achieve it, ->probe() call added to all mxl111sf_*
> devices, which will simply initiaize mutex.
> 
> Reported-and-tested-by: syzbot+5ca0bf339f13c4243001@...kaller.appspotmail.com
> Fixes: 8572211842af ("[media] mxl111sf: convert to new DVB USB")
> Signed-off-by: Pavel Skripkin <paskripkin@...il.com>

Hi, Sean!

Did you have a chance to review this patch? Thank you :)


With regards,
Pavel Skripkin