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Subject[ 43/77] ext4: fix possible use-after-free with AIO
Date
3.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jan Kara <jack@suse.cz>

commit 091e26dfc156aeb3b73bc5c5f277e433ad39331c upstream.

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.

Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/ext4/inode.c | 2 +-
fs/ext4/page-io.c | 9 ++++-----
2 files changed, 5 insertions(+), 6 deletions(-)

--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2977,9 +2977,9 @@ static void ext4_end_io_dio(struct kiocb
if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
ext4_free_io_end(io_end);
out:
+ inode_dio_done(inode);
if (is_async)
aio_complete(iocb, ret, 0);
- inode_dio_done(inode);
return;
}

--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -103,14 +103,13 @@ static int ext4_end_io(ext4_io_end_t *io
"(inode %lu, offset %llu, size %zd, error %d)",
inode->i_ino, offset, size, ret);
}
- if (io->iocb)
- aio_complete(io->iocb, io->result, 0);
-
- if (io->flag & EXT4_IO_END_DIRECT)
- inode_dio_done(inode);
/* Wake up anyone waiting on unwritten extent conversion */
if (atomic_dec_and_test(&EXT4_I(inode)->i_unwritten))
wake_up_all(ext4_ioend_wq(inode));
+ if (io->flag & EXT4_IO_END_DIRECT)
+ inode_dio_done(inode);
+ if (io->iocb)
+ aio_complete(io->iocb, io->result, 0);
return ret;
}




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