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From: Christoph Hellwig <hch@lst.de>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>, Avi Kivity <avi@scylladb.com>,
	linux-aio@kvack.org, linux-fsdevel@vger.kernel.org,
	linux-api@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/6] aio: refactor read/write iocb setup
Date: Fri, 6 Apr 2018 09:10:11 +0200	[thread overview]
Message-ID: <20180406071011.GA21308@lst.de> (raw)
In-Reply-To: <20180406032146.GV30522@ZenIV.linux.org.uk>

On Fri, Apr 06, 2018 at 04:21:46AM +0100, Al Viro wrote:
> On Wed, Mar 28, 2018 at 09:26:36AM +0200, Christoph Hellwig wrote:
> > +		struct inode *inode = file_inode(file);
> > +
> >  		req->ki_flags |= IOCB_WRITE;
> >  		file_start_write(file);
> > -		ret = aio_ret(req, call_write_iter(file, req, &iter));
> > +		ret = aio_rw_ret(req, call_write_iter(file, req, &iter));
> >  		/*
> > -		 * We release freeze protection in aio_complete().  Fool lockdep
> > -		 * by telling it the lock got released so that it doesn't
> > -		 * complain about held lock when we return to userspace.
> > +		 * We release freeze protection in aio_complete_rw().  Fool
> > +		 * lockdep by telling it the lock got released so that it
> > +		 * doesn't complain about held lock when we return to userspace.
> >  		 */
> > -		if (S_ISREG(file_inode(file)->i_mode))
> > -			__sb_writers_release(file_inode(file)->i_sb, SB_FREEZE_WRITE);
> > +		if (S_ISREG(inode->i_mode))
> 
> ... and that's another use-after-free, since we might've already done fput() of
> that sucker by that point.

Indeed.  Not in any way new in this patch, this is an existing issue
dating way back that needs to be fixed, which will be rather annoying
without taking an extra reference to the inode or at least sb.

WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>, Avi Kivity <avi@scylladb.com>,
	linux-aio@kvack.org, linux-fsdevel@vger.kernel.org,
	linux-api@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/6] aio: refactor read/write iocb setup
Date: Fri, 6 Apr 2018 09:10:11 +0200	[thread overview]
Message-ID: <20180406071011.GA21308@lst.de> (raw)
In-Reply-To: <20180406032146.GV30522@ZenIV.linux.org.uk>

On Fri, Apr 06, 2018 at 04:21:46AM +0100, Al Viro wrote:
> On Wed, Mar 28, 2018 at 09:26:36AM +0200, Christoph Hellwig wrote:
> > +		struct inode *inode = file_inode(file);
> > +
> >  		req->ki_flags |= IOCB_WRITE;
> >  		file_start_write(file);
> > -		ret = aio_ret(req, call_write_iter(file, req, &iter));
> > +		ret = aio_rw_ret(req, call_write_iter(file, req, &iter));
> >  		/*
> > -		 * We release freeze protection in aio_complete().  Fool lockdep
> > -		 * by telling it the lock got released so that it doesn't
> > -		 * complain about held lock when we return to userspace.
> > +		 * We release freeze protection in aio_complete_rw().  Fool
> > +		 * lockdep by telling it the lock got released so that it
> > +		 * doesn't complain about held lock when we return to userspace.
> >  		 */
> > -		if (S_ISREG(file_inode(file)->i_mode))
> > -			__sb_writers_release(file_inode(file)->i_sb, SB_FREEZE_WRITE);
> > +		if (S_ISREG(inode->i_mode))
> 
> ... and that's another use-after-free, since we might've already done fput() of
> that sucker by that point.

Indeed.  Not in any way new in this patch, this is an existing issue
dating way back that needs to be fixed, which will be rather annoying
without taking an extra reference to the inode or at least sb.

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  reply	other threads:[~2018-04-06  7:10 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-28  7:26 io_pgetevents & aio fsync V2 Christoph Hellwig
2018-03-28  7:26 ` Christoph Hellwig
2018-03-28  7:26 ` [PATCH 1/6] aio: don't print the page size at boot time Christoph Hellwig
2018-03-28  7:26   ` Christoph Hellwig
2018-03-28  7:26 ` [PATCH 2/6] aio: remove an outdated comment in aio_complete Christoph Hellwig
2018-03-28  7:26   ` Christoph Hellwig
2018-03-28 16:05   ` Darrick J. Wong
2018-03-28 16:05     ` Darrick J. Wong
2018-03-28 17:05   ` Matthew Wilcox
2018-03-28 17:05     ` Matthew Wilcox
2018-03-28  7:26 ` [PATCH 3/6] aio: refactor read/write iocb setup Christoph Hellwig
2018-03-28  7:26   ` Christoph Hellwig
2018-04-06  3:21   ` Al Viro
2018-04-06  3:21     ` Al Viro
2018-04-06  7:10     ` Christoph Hellwig [this message]
2018-04-06  7:10       ` Christoph Hellwig
2018-04-06 12:28       ` Al Viro
2018-04-06 12:28         ` Al Viro
2018-03-28  7:26 ` [PATCH 4/6] aio: sanitize ki_list handling Christoph Hellwig
2018-03-28  7:26   ` Christoph Hellwig
2018-03-28  7:26 ` [PATCH 5/6] aio: implement IOCB_CMD_FSYNC and IOCB_CMD_FDSYNC Christoph Hellwig
2018-03-28  7:26   ` Christoph Hellwig
2018-04-06  2:59   ` Al Viro
2018-04-06  2:59     ` Al Viro
2018-03-28  7:26 ` [PATCH 6/6] aio: implement io_pgetevents Christoph Hellwig
2018-03-28  7:26   ` Christoph Hellwig
2018-04-06  3:16 ` io_pgetevents & aio fsync V2 Al Viro
2018-04-06  3:16   ` Al Viro
2018-04-06  6:27   ` Christoph Hellwig
2018-04-06  6:27     ` Christoph Hellwig
2018-04-06 12:57     ` Jeff Moyer
2018-04-06 12:57       ` Jeff Moyer

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