linux-kernel - Re: [git pull] gadgetfs fixes

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Message-ID: <55052828.7090701@ahsoftware.de>
Date:	Sun, 15 Mar 2015 07:35:20 +0100
From:	Alexander Holler <holler@...oftware.de>
To:	Al Viro <viro@...IV.linux.org.uk>
CC:	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	linux-usb@...r.kernel.org
Subject: Re: [git pull] gadgetfs fixes

Am 15.03.2015 um 02:39 schrieb Al Viro:
> On Sun, Mar 15, 2015 at 01:39:21AM +0100, Alexander Holler wrote:
>> Am 13.03.2015 um 17:42 schrieb Al Viro:
>>> 	Assorted fixes around AIO on gadgetfs: leaks, use-after-free,
>>> troubles caused by ->f_op flipping.  Please, pull from
>>> git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git gadget
>>>
>>> Shortlog:
>>> Al Viro (8):
>>>       new helper: dup_iter()
>>>       move iov_iter.c from mm/ to lib/
>>>       gadget/function/f_fs.c: close leaks
>>>       gadget/function/f_fs.c: use put iov_iter into io_data
>>>       gadget/function/f_fs.c: switch to ->{read,write}_iter()
>>
>>>       gadgetfs: use-after-free in ->aio_read()
>>
>> If that patch ends up in the stable kernels (as it is marked as such),
>> it needs a
>> 	value = -ENOMEM
>> before that added "goto fail;", otherwise the return value is unitialized.
> 
> Umm...  If I'm not misparsing what you said, you are talking about the

Glücklicherweise nicht. Vielleicht sollten wir es zur Abwechslung mal
mit meiner bevorzugten Sprache versuchen.

> one that gets removed by
> -       if (iv) {
> -               priv->iv = kmemdup(iv, nr_segs * sizeof(struct iovec),
> -                                  GFP_KERNEL);
> -               if (!priv->iv) {
> -                       kfree(priv);
> -                       goto fail;
> -               }
> -       }
> in "gadget: switch ep_io_operations to ->read_iter/->write_iter" very
> shortly afterwards, and _that_ is a prereq for ->f_op flipping fixes,
> which is also clear -stable fodder.  But yes, it's a bisect hazard and
> a cherry-pick one as well.  Nice catch...

The following patches aren't marked for stable, otherwise I would not
have risked to become a victim of your comments again.

Alexander Holler
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