xfs: Fix possible use-after-free with AIO

commit 4b05d09c18d9aa62d2e7fb4b057f54e5a38963f5 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.

CC: xfs@oss.sgi.com
CC: Ben Myers <bpm@sgi.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ben Myers <bpm@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 574d4ee..b367581 100644 (file)
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -88,11 +88,11 @@ xfs_destroy_ioend(
        }
 
        if (ioend->io_iocb) {
+               inode_dio_done(ioend->io_inode);
                if (ioend->io_isasync) {
                        aio_complete(ioend->io_iocb, ioend->io_error ?
                                        ioend->io_error : ioend->io_result, 0);
                }
-               inode_dio_done(ioend->io_inode);
        }
 
        mempool_free(ioend, xfs_ioend_pool);