Hi Chao,
On Wed, Jul 02, 2014 at 01:23:47PM +0800, Chao Yu wrote:
> We assume that modification of some special application could result in zeroed
> name_len, or it is consciously made by somebody. We will deadloop in
> find_in_block when name_len of dir entry is zero.
Could you explain this a little bit more?
I'm not sure how it can happen.
I think the zeroed name_len would cause some problems in f2fs_add_link.
Thanks,
>
> This patch is added for preventing deadloop in above scenario.
>
> Signed-off-by: Chao Yu <chao2.yu@xxxxxxxxxxx>
> ---
> fs/f2fs/dir.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
> index be8c7af..4316ec5 100644
> --- a/fs/f2fs/dir.c
> +++ b/fs/f2fs/dir.c
> @@ -121,6 +121,16 @@ static struct f2fs_dir_entry *find_in_block(struct page *dentry_page,
> }
> }
>
> + /* check name_len to prevent from deadloop here */
> + if (unlikely(de->name_len == 0)) {
> + struct inode *inode = dentry_page->mapping->host;
> +
> + f2fs_msg(inode->i_sb, KERN_ERR,
> + "zero-length dir entry, ino = %lu, name = %s",
> + (unsigned long)inode->i_ino, name->name);
> + break;
> + }
> +
> bit_start = bit_pos
> + GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
> }
> --
> 1.7.9.5
--
Jaegeuk Kim
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