linux-kernel - [PATCH 1/4] aio: hold an extra file reference over AIO read/write operations

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Date:   Sun, 30 Oct 2016 11:42:01 -0500
From:   Christoph Hellwig <hch@....de>
To:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Al Viro <viro@...iv.linux.org.uk>
Cc:     Jan Kara <jack@...e.cz>, Dmitry Monakhov <dmonakhov@...nvz.org>,
        Jeff Moyer <jmoyer@...hat.com>, linux-fsdevel@...r.kernel.org,
        linux-aio@...ck.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/4] aio: hold an extra file reference over AIO read/write operations

Otherwise we might dereference an already freed file and/or inode
when aio_complete is called before we return from the read_iter or
write_iter method.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 fs/aio.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/aio.c b/fs/aio.c
index 1157e13..0aa71d3 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1460,6 +1460,7 @@ static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode,
 			return ret;
 		}
 
+		get_file(file);
 		if (rw == WRITE)
 			file_start_write(file);
 
@@ -1467,6 +1468,7 @@ static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode,
 
 		if (rw == WRITE)
 			file_end_write(file);
+		fput(file);
 		kfree(iovec);
 		break;
 
-- 
2.1.4