Commit 4d34b278 authored by Ilya Dryomov's avatar Ilya Dryomov
Browse files

Btrfs: avoid null dereference and leaks when bailing from open_ctree() 



Fix bugs introduced by 6c41761f.  Firstly, after failing to allocate any
of the tree roots (first 'goto fail' in open_ctree()) we would
dereference a NULL fs_info pointer in free_fs_info().  Secondly, after
failures from init_srcu_struct(), setup_bdi() and new_inode() we would
leak all earlier allocated roots: fs_info fields haven't been
initialized yet so free_fs_info() is rendered useless.

Fix this by initializing fs_info pointer and fs_info fields before any
allocations happen.

Signed-off-by: default avatarIlya Dryomov <idryomov@gmail.com>
parent f23c8af8

fs/btrfs/disk-io.c

+15 −20
Original line number Diff line number Diff line
@@ -1890,31 +1890,32 @@ struct btrfs_root *open_ctree(struct super_block *sb, 
	u64 features;

	struct btrfs_key location;

	struct buffer_head *bh;

	struct btrfs_root *extent_root = kzalloc(sizeof(struct btrfs_root),

						 GFP_NOFS);

	struct btrfs_root *csum_root = kzalloc(sizeof(struct btrfs_root),

						 GFP_NOFS);

	struct btrfs_super_block *disk_super;

	struct btrfs_root *tree_root = btrfs_sb(sb);

	struct btrfs_fs_info *fs_info = NULL;

	struct btrfs_root *chunk_root = kzalloc(sizeof(struct btrfs_root),

						GFP_NOFS);

	struct btrfs_root *dev_root = kzalloc(sizeof(struct btrfs_root),

					      GFP_NOFS);

	struct btrfs_fs_info *fs_info = tree_root->fs_info;

	struct btrfs_root *extent_root;

	struct btrfs_root *csum_root;

	struct btrfs_root *chunk_root;

	struct btrfs_root *dev_root;

	struct btrfs_root *log_tree_root;



	int ret;

	int err = -EINVAL;

	int num_backups_tried = 0;

	int backup_index = 0;



	struct btrfs_super_block *disk_super;

	extent_root = fs_info->extent_root =

		kzalloc(sizeof(struct btrfs_root), GFP_NOFS);

	csum_root = fs_info->csum_root =

		kzalloc(sizeof(struct btrfs_root), GFP_NOFS);

	chunk_root = fs_info->chunk_root =

		kzalloc(sizeof(struct btrfs_root), GFP_NOFS);

	dev_root = fs_info->dev_root =

		kzalloc(sizeof(struct btrfs_root), GFP_NOFS);



	if (!extent_root || !tree_root || !tree_root->fs_info ||

	    !chunk_root || !dev_root || !csum_root) {

	if (!extent_root || !csum_root || !chunk_root || !dev_root) {

		err = -ENOMEM;

		goto fail;

	}

	fs_info = tree_root->fs_info;



	ret = init_srcu_struct(&fs_info->subvol_srcu);

	if (ret) {
@@ -1954,12 +1955,6 @@ struct btrfs_root *open_ctree(struct super_block *sb, 
	mutex_init(&fs_info->reloc_mutex);



	init_completion(&fs_info->kobj_unregister);

	fs_info->tree_root = tree_root;

	fs_info->extent_root = extent_root;

	fs_info->csum_root = csum_root;

	fs_info->chunk_root = chunk_root;

	fs_info->dev_root = dev_root;

	fs_info->fs_devices = fs_devices;

	INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);

	INIT_LIST_HEAD(&fs_info->space_info);

	btrfs_mapping_init(&fs_info->mapping_tree);

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