From: Jan Kara <jack@suse.cz>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>, Christoph Hellwig <hch@lst.de>,
Jan Kara <jack@suse.cz>, Dmitry Monakhov <dmonakhov@openvz.org>,
Jeff Moyer <jmoyer@redhat.com>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
linux-aio@kvack.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
stable <stable@vger.kernel.org>
Subject: Re: [PATCH] aio: fix a user triggered use after free (and fix freeze protection of aio writes)
Date: Sun, 30 Oct 2016 10:44:37 +0100 [thread overview]
Message-ID: <20161030094437.GA3225@quack2.suse.cz> (raw)
In-Reply-To: <CA+55aFy3rYRDSHGfxrF-nTRKoxHB1-Kk63Z3xDN3cSRLbx1BbA@mail.gmail.com>
On Sat 29-10-16 13:09:25, Linus Torvalds wrote:
> On Sat, Oct 29, 2016 at 12:17 PM, Al Viro <viro@zeniv.linux.org.uk> wrote:
> >
> > AFAICS, the possibility of dropping the last reference to struct file
> > before ->write_iter() has returned is fundamentally broken. I might be
> > missing something subtle here, but...
>
> Ok, let's add a get_file(); fput(); around that whole iter call sequence.
>
> And that's a separate issue from "we should hold the fs freezer lock
> around the whole operation". So I think we need both.
Yup, these are two separate issues. I'm fine with adding get_file(); fput()
around the iter call sequence. Then, when we have struct file available for
the whole time ->write_iter runs, I'd prefer to keep the call to fool
lockdep where original file_end_write() call was - that gives us proper
lockdep coverage for all the code behind iter_op(). The downside is we
cannot keep helpers as elegant as you suggested in your patch but I believe
it's bearable and worth the additional lockdep coverage. I'll send patches
shortly...
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
next prev parent reply other threads:[~2016-10-30 9:44 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1477727070-18806-1-git-send-email-hch@lst.de>
2016-10-29 7:44 ` [PATCH] aio: fix a user triggered use after free (and fix freeze protection of aio writes) Christoph Hellwig
2016-10-29 12:24 ` Al Viro
2016-10-29 15:20 ` Christoph Hellwig
2016-10-29 16:12 ` Al Viro
2016-10-29 16:29 ` Al Viro
2016-10-30 6:32 ` Christoph Hellwig
2016-10-29 17:47 ` Linus Torvalds
2016-10-29 18:52 ` Al Viro
2016-10-29 19:07 ` Linus Torvalds
2016-10-29 19:17 ` Al Viro
2016-10-29 20:09 ` Linus Torvalds
2016-10-30 9:44 ` Jan Kara [this message]
2016-10-30 10:52 ` Jan Kara
2016-10-30 15:58 ` Christoph Hellwig
2016-10-30 6:29 ` Christoph Hellwig
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