ext4: 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: [email protected] Reviewed-by: Carlos Maiolino <[email protected]> Acked-by: Jeff Moyer <[email protected]> Signed-off-by: Jan Kara <[email protected]> Signed-off-by: "Theodore Ts'o" <[email protected]>
bpopovych · Jan 30, 2013 · 091e26d · 091e26d
1 parent b1deefc
commit 091e26d
Show file tree

Hide file tree

Showing 2 changed files with 5 additions and 6 deletions.
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
@@ -2850,9 +2850,9 @@ static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
 	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;
 	}
 

diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
@@ -102,14 +102,13 @@ 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;
 }