From: "Aurélien Aptel" <aaptel@suse.com>
To: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: sfrench@samba.org, linux-cifs@vger.kernel.org
Subject: Re: v5.1-rc1 cifs bug: underflow; use-after-free.
Date: Wed, 20 Mar 2019 12:12:21 +0100 [thread overview]
Message-ID: <871s316bqi.fsf@suse.com> (raw)
In-Reply-To: <20190319162645.GA3498@light.dominikbrodowski.net>
Dominik Brodowski <linux@dominikbrodowski.net> writes:
> Thanks for taking a look at this issue. Fortunately, it is easily
> reproducable (at least for me).
Which server are you doing this against? I couldn't reproduce against
Windows Server 2016.
>> If you enable verbose debugging [1], if my theory is correct you should
>> see a lease break messsage followed by "clear cached root file handle"
>> message before the warning.
>
> Hm, no.
Ok well I'm not sure what is happening then. But the final points still
stand:
- since we don't free anything in the release function, there is no
use-after-free.
- the access to the kref is already protected by crfid.fid_mutex so we
could replace it with a regular int and avoid the warning generated by
kref_put() that you see.
--
Aurélien Aptel / SUSE Labs Samba Team
GPG: 1839 CB5F 9F5B FB9B AA97 8C99 03C8 A49B 521B D5D3
SUSE Linux GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
next prev parent reply other threads:[~2019-03-20 11:12 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-19 11:51 v5.1-rc1 cifs bug: underflow; use-after-free Dominik Brodowski
2019-03-19 15:26 ` Aurélien Aptel
2019-03-19 15:47 ` Aurélien Aptel
2019-03-19 16:26 ` Dominik Brodowski
2019-03-20 11:12 ` Aurélien Aptel [this message]
2019-03-26 7:18 ` Dominik Brodowski
2019-03-26 12:39 ` [PATCH v1] CIFS: prevent refcount underflow Aurelien Aptel
2019-03-26 15:46 ` Dominik Brodowski
2019-03-26 16:53 ` Aurélien Aptel
2019-03-26 16:53 ` Dominik Brodowski
2019-03-27 22:36 ` Pavel Shilovsky
2019-03-27 23:44 ` ronnie sahlberg
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