linux-kernel - Re: gigaset: freeing an active object

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Message-ID: <565B460D.9080002@imap.cc>
Date:	Sun, 29 Nov 2015 19:38:05 +0100
From:	Tilman Schmidt <tilman@...p.cc>
To:	Peter Hurley <peter@...leysoftware.com>,
	Sasha Levin <sasha.levin@...cle.com>
Cc:	pebolle@...cali.nl, isdn@...ux-pingi.de, davem@...emloft.net,
	gigaset307x-common@...ts.sourceforge.net,
	LKML <linux-kernel@...r.kernel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	syzkaller <syzkaller@...glegroups.com>
Subject: Re: gigaset: freeing an active object

Am 29.11.2015 um 19:22 schrieb Peter Hurley:
> On 11/29/2015 10:30 AM, Tilman Schmidt wrote:
>>
>> Judging from the backtrace below this must be the call
>>
>>         kfree(cs->hw.ser);
>>
>> in drivers/isdn/gigaset/ser-gigaset.c line 375.
>> cs->hw.ser is of type struct ser_cardstate *.
>> struct ser_cardstate consists of a struct platform_device, a struct
>> completion, an atomic_t and a pointer. No timer_list.
[...]
> 
> The platform_device embedded in struct ser_cardstate hasn't been released when
> you kfree() the memory it's in.

How so? The kfree() call quoted above is immediately preceded by:

        platform_device_unregister(&cs->hw.ser->dev);

Thanks,
Tilman

-- 
Tilman Schmidt                              E-Mail: tilman@...p.cc
Bonn, Germany
Nous, on a des fleurs et des bougies pour nous protéger.


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