Btrfs: open_ctree() error handling can oops on fs_info

a bug in open_ctree:

struct btrfs_root *open_ctree(..)
{
....
	if (!extent_root || !tree_root || !fs_info ||
	    !chunk_root || !dev_root || !csum_root) {
		err = -ENOMEM;
		goto fail;
//When code flow goes to "fail", fs_info may be NULL or uninitialized.
	}
....

fail:
	btrfs_close_devices(fs_info->fs_devices);// !
	btrfs_mapping_tree_free(&fs_info->mapping_tree);// !

	kfree(extent_root);
	kfree(tree_root);
	bdi_destroy(&fs_info->bdi);// !
...
)

Signed-off-by: Qinghuang Feng <qhfeng.kernel@gmail.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 26a18779e84bb3df55e62f79630218010202326e..3cf17257f89dca5f1e8b5d0041e170a6da22aa37 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1823,13 +1823,14 @@ fail_sb_buffer:
 fail_iput:
        invalidate_inode_pages2(fs_info->btree_inode->i_mapping);
        iput(fs_info->btree_inode);
-fail:
+
        btrfs_close_devices(fs_info->fs_devices);
        btrfs_mapping_tree_free(&fs_info->mapping_tree);
+       bdi_destroy(&fs_info->bdi);
 
+fail:
        kfree(extent_root);
        kfree(tree_root);
-       bdi_destroy(&fs_info->bdi);
        kfree(fs_info);
        kfree(chunk_root);
        kfree(dev_root);