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From: Pavel Skripkin <paskripkin@gmail.com>
To: Sean Young <sean@mess.org>
Cc: mkrufky@linuxtv.org, mchehab@kernel.org, crope@iki.fi,
	linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
	syzbot+5ca0bf339f13c4243001@syzkaller.appspotmail.com
Subject: Re: [PATCH] media: mxl111sf: change mutex_init() location
Date: Sun, 15 Aug 2021 11:49:26 +0300	[thread overview]
Message-ID: <7ee99788-d9a5-0a38-ed02-51d9b42ebc11@gmail.com> (raw)
In-Reply-To: <20210815083755.GA1827@gofer.mess.org>

On 8/15/21 11:37 AM, Sean Young wrote:
> On Sat, Jul 31, 2021 at 12:38:29AM +0300, 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_frontend_attach_atsc_mh() calls mxl111sf_ctrl_msg()
>> internally we need to initialize state->msg_lock in it to make lockdep
>> happy.
> 
> What about the other frontends like mxl111sf_frontend_attach_dvbt? They
> no longer initialize the mutex.
> 
Good point. I see, that all other frontends also call 
mxl111sf_ctrl_msg() inside ->frontend_attach() call.

I think, that fixing dvb-usb core is not good idea, so, I will add 
mutex_init() call inside all frontends, which use mxl111sf_init().

What do you think about it?


With regards,
Pavel Skripkin

  reply	other threads:[~2021-08-15  8:49 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-30 21:38 [PATCH] media: mxl111sf: change mutex_init() location Pavel Skripkin
2021-08-15  8:37 ` Sean Young
2021-08-15  8:49   ` Pavel Skripkin [this message]
2021-08-15  9:06     ` Pavel Skripkin
2021-08-19  9:29       ` Sean Young
2021-08-19  9:31         ` Pavel Skripkin
2021-08-19 10:38         ` [PATCH v2] " Pavel Skripkin
2021-08-19 10:42           ` [PATCH v3] " Pavel Skripkin
2021-09-12 15:49             ` Pavel Skripkin
2021-09-15 16:40               ` Sean Young

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