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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: Su Yue <suy.fnst@cn.fujitsu.com> Reviewed-by: David Sterba <dsterba@suse.com> [ s/btrfs_leaf_data/BTRFS_LEAF_DATA_OFFSET/ ] Signed-off-by: David Sterba <dsterba@suse.com>
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2 changed files with 74 additions and 0 deletions
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@ -3042,6 +3042,8 @@ struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_fs_info *fs_info,
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struct btrfs_path *path,
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const char *name,
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int name_len);
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bool btrfs_is_name_len_valid(struct extent_buffer *leaf, int slot,
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unsigned long start, u16 name_len);
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/* orphan.c */
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int btrfs_insert_orphan_item(struct btrfs_trans_handle *trans,
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@ -484,3 +484,75 @@ int verify_dir_item(struct btrfs_fs_info *fs_info,
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return 0;
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}
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bool btrfs_is_name_len_valid(struct extent_buffer *leaf, int slot,
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unsigned long start, u16 name_len)
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{
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struct btrfs_fs_info *fs_info = leaf->fs_info;
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struct btrfs_key key;
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u32 read_start;
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u32 read_end;
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u32 item_start;
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u32 item_end;
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u32 size;
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bool ret = true;
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ASSERT(start > BTRFS_LEAF_DATA_OFFSET);
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read_start = start - BTRFS_LEAF_DATA_OFFSET;
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read_end = read_start + name_len;
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item_start = btrfs_item_offset_nr(leaf, slot);
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item_end = btrfs_item_end_nr(leaf, slot);
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btrfs_item_key_to_cpu(leaf, &key, slot);
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switch (key.type) {
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case BTRFS_DIR_ITEM_KEY:
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case BTRFS_XATTR_ITEM_KEY:
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case BTRFS_DIR_INDEX_KEY:
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size = sizeof(struct btrfs_dir_item);
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break;
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case BTRFS_INODE_REF_KEY:
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size = sizeof(struct btrfs_inode_ref);
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break;
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case BTRFS_INODE_EXTREF_KEY:
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size = sizeof(struct btrfs_inode_extref);
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break;
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case BTRFS_ROOT_REF_KEY:
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case BTRFS_ROOT_BACKREF_KEY:
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size = sizeof(struct btrfs_root_ref);
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break;
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default:
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ret = false;
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goto out;
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}
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if (read_start < item_start) {
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ret = false;
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goto out;
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}
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if (read_end > item_end) {
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ret = false;
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goto out;
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}
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/* there shall be item(s) before name */
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if (read_start - item_start < size) {
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ret = false;
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goto out;
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}
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/*
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* This may be the last item in the slot
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* Or same type item(s) is left between read_end and item_end
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*/
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if (item_end != read_end && item_end - read_end < size) {
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ret = false;
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goto out;
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}
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out:
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if (!ret)
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btrfs_crit(fs_info, "invalid dir item name len: %u",
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(unsigned int)name_len);
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return ret;
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}
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