On 17.01.2018 07:17, Qu Wenruo wrote:
> Function btrfs_delete_one_dir_name() will check if the dir_item is the
> last content of the item, and delete the whole item if needed.
> 
> However if @name_len of one dir_item/dir_index is corrupted and larger
> than the item size, the function will still try to treat it as partly
> remove, which will screw up the whole leaf.
> 
> This patch will enhance the item deletion check, to cover corrupted name
> len, so in that case we just delete the whole item.
> 
> Signed-off-by: Qu Wenruo <w...@suse.com>

Reviewed-by: Nikolay Borisov <nbori...@suse.com>

> ---
>  dir-item.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/dir-item.c b/dir-item.c
> index 31ad1eca29d5..7ce3d2a40433 100644
> --- a/dir-item.c
> +++ b/dir-item.c
> @@ -281,7 +281,6 @@ int btrfs_delete_one_dir_name(struct btrfs_trans_handle 
> *trans,
>                             struct btrfs_path *path,
>                             struct btrfs_dir_item *di)
>  {
> -
>       struct extent_buffer *leaf;
>       u32 sub_item_len;
>       u32 item_len;
> @@ -291,7 +290,15 @@ int btrfs_delete_one_dir_name(struct btrfs_trans_handle 
> *trans,
>       sub_item_len = sizeof(*di) + btrfs_dir_name_len(leaf, di) +
>               btrfs_dir_data_len(leaf, di);
>       item_len = btrfs_item_size_nr(leaf, path->slots[0]);
> -     if (sub_item_len == item_len) {
> +
> +     /*
> +      * If @sub_item_len is longer than @item_len, then it means the
> +      * name_len is just corrupted.
> +      * No good idea to know if there is anything we can recover from
> +      * the corrupted item.
> +      * Just delete the item.
> +      */
> +     if (sub_item_len >= item_len) {
>               ret = btrfs_del_item(trans, root, path);
>       } else {
>               unsigned long ptr = (unsigned long)di;
> 
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