linux-kernel - Re: [PATCH v3 3/6] floppy: avoid leaking extra reference to queue on do_floppy

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20120814090330.GC2423@redhat.com>
Date:	Tue, 14 Aug 2012 11:03:30 +0200
From:	Stanislaw Gruszka <sgruszka@...hat.com>
To:	Ben Hutchings <ben@...adent.org.uk>
Cc:	Herton Ronaldo Krzesinski <herton.krzesinski@...onical.com>,
	Jens Axboe <axboe@...nel.dk>, Jiri Kosina <jkosina@...e.cz>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Tejun Heo <tj@...nel.org>, linux-kernel@...r.kernel.org,
	Vivek Goyal <vgoyal@...hat.com>
Subject: Re: [PATCH v3 3/6] floppy: avoid leaking extra reference to queue on
 do_floppy_init error handling

On Tue, Aug 14, 2012 at 04:20:39AM +0100, Ben Hutchings wrote:
> On Mon, 2012-08-13 at 15:16 -0300, Herton Ronaldo Krzesinski wrote:
> > After commit 3f9a5aa ("floppy: Cleanup disk->queue before caling
> > put_disk() if add_disk() was never called"), if something fails in the
> > add_disk loop, we unconditionally set disks[dr]->queue to NULL. But
> > that's wrong, since we may have succesfully done an add_disk on some of
> > the drives previously in the loop, and in this case we would end up with
> > an extra reference to the disks[dr]->queue.
> > 
> > Add a new global array to mark "registered" disks, and use that to check
> > if we did an add_disk on one of the disks already. Using an array to
> > track added disks also will help to simplify/cleanup code later, as
> > suggested by Vivek Goyal.
> [...]
> 
> It's totally ridiculous that a driver should have to do this.  Any
> registered disk should have the GENHD_FL_UP flag set... so why can't
> genhd check it?  It doesn't look like floppy is the only driver affected
> by this problem, either.  So I suggest the following general fix
> (untested):
> 
> ---
> Subject: genhd: Make put_disk() safe for disks that have not been registered
> 
> Since commit 9f53d2f ('block: fix __blkdev_get and add_disk race
> condition'), add_disk() adds a reference to disk->queue,

I do not see this? Commit 9f53d2fe insert disk_alloc_events() to add_disk(),
but disk_alloc_events() function does not get any reference to disk->queue,
I missed something?

Stanislaw
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/