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Commit 19c6dcbf authored by Su Yue's avatar Su Yue Committed by David Sterba
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btrfs: Introduce btrfs_is_name_len_valid to avoid reading beyond boundary 



Introduce function btrfs_is_name_len_valid.

The function compares parameter @name_len with item boundary then
returns true if name_len is valid.

Signed-off-by: default avatarSu Yue <suy.fnst@cn.fujitsu.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
[ s/btrfs_leaf_data/BTRFS_LEAF_DATA_OFFSET/ ]
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 66b4993e

fs/btrfs/ctree.h

+2 −0
Original line number Diff line number Diff line
@@ -3042,6 +3042,8 @@ struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_fs_info *fs_info, 
						 struct btrfs_path *path,

						 const char *name,

						 int name_len);

bool btrfs_is_name_len_valid(struct extent_buffer *leaf, int slot,

			     unsigned long start, u16 name_len);



/* orphan.c */

int btrfs_insert_orphan_item(struct btrfs_trans_handle *trans,

fs/btrfs/dir-item.c

+72 −0
Original line number Diff line number Diff line
@@ -484,3 +484,75 @@ int verify_dir_item(struct btrfs_fs_info *fs_info, 


	return 0;

}



bool btrfs_is_name_len_valid(struct extent_buffer *leaf, int slot,

			     unsigned long start, u16 name_len)

{

	struct btrfs_fs_info *fs_info = leaf->fs_info;

	struct btrfs_key key;

	u32 read_start;

	u32 read_end;

	u32 item_start;

	u32 item_end;

	u32 size;

	bool ret = true;



	ASSERT(start > BTRFS_LEAF_DATA_OFFSET);



	read_start = start - BTRFS_LEAF_DATA_OFFSET;

	read_end = read_start + name_len;

	item_start = btrfs_item_offset_nr(leaf, slot);

	item_end = btrfs_item_end_nr(leaf, slot);



	btrfs_item_key_to_cpu(leaf, &key, slot);



	switch (key.type) {

	case BTRFS_DIR_ITEM_KEY:

	case BTRFS_XATTR_ITEM_KEY:

	case BTRFS_DIR_INDEX_KEY:

		size = sizeof(struct btrfs_dir_item);

		break;

	case BTRFS_INODE_REF_KEY:

		size = sizeof(struct btrfs_inode_ref);

		break;

	case BTRFS_INODE_EXTREF_KEY:

		size = sizeof(struct btrfs_inode_extref);

		break;

	case BTRFS_ROOT_REF_KEY:

	case BTRFS_ROOT_BACKREF_KEY:

		size = sizeof(struct btrfs_root_ref);

		break;

	default:

		ret = false;

		goto out;

	}



	if (read_start < item_start) {

		ret = false;

		goto out;

	}

	if (read_end > item_end) {

		ret = false;

		goto out;

	}



	/* there shall be item(s) before name */

	if (read_start - item_start < size) {

		ret = false;

		goto out;

	}



	/*

	 * This may be the last item in the slot

	 * Or same type item(s) is left between read_end and item_end

	 */

	if (item_end != read_end && item_end - read_end < size) {

		ret = false;

		goto out;

	}

out:

	if (!ret)

		btrfs_crit(fs_info, "invalid dir item name len: %u",

			   (unsigned int)name_len);

	return ret;

}