linux-ext4 - [PATCH 4/4] fs: Fix possible use-after-free with AIO

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Date:	Wed, 30 Jan 2013 00:28:01 +0100
From:	Jan Kara <jack@...e.cz>
To:	Al Viro <viro@...IV.linux.org.uk>
Cc:	linux-fsdevel@...r.kernel.org, xfs@....sgi.com,
	linux-ext4@...r.kernel.org, ocfs2-devel@....oracle.com,
	Jan Kara <jack@...e.cz>, Christoph Hellwig <hch@...radead.org>,
	Jens Axboe <axboe@...nel.dk>, Jeff Moyer <jmoyer@...hat.com>,
	stable@...r.kernel.org
Subject: [PATCH 4/4] fs: Fix possible use-after-free with AIO

Running AIO is pinning inode in memory using file reference. Once AIO
is completed using aio_complete(), file reference is put and inode can
be freed from memory. So we have to be sure that calling aio_complete()
is the last thing we do with the inode.

CC: Christoph Hellwig <hch@...radead.org>
CC: Jens Axboe <axboe@...nel.dk>
CC: Jeff Moyer <jmoyer@...hat.com>
CC: stable@...r.kernel.org
Acked-by: Jeff Moyer <jmoyer@...hat.com>
Signed-off-by: Jan Kara <jack@...e.cz>
---
 fs/direct-io.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/fs/direct-io.c b/fs/direct-io.c
index cf5b44b..f853263 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -261,9 +261,9 @@ static ssize_t dio_complete(struct dio *dio, loff_t offset, ssize_t ret, bool is
 		dio->end_io(dio->iocb, offset, transferred,
 			    dio->private, ret, is_async);
 	} else {
+		inode_dio_done(dio->inode);
 		if (is_async)
 			aio_complete(dio->iocb, ret, 0);
-		inode_dio_done(dio->inode);
 	}
 
 	return ret;
-- 
1.7.1

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