On Fri, Oct 21, 2016 at 02:48:35PM +0200, Richard Weinberger wrote:
> +
> +     if (!dentry)
> +             return ERR_PTR(-ECHILD);
> +
> +     if (ubifs_crypt_is_encrypted(inode)) {
> +             err = fscrypt_get_encryption_info(inode);
> +             if (err)
> +                     return ERR_PTR(err);
> +     } else
> +             return ui->data;
> +

This will make path lookups drop out of RCU mode when an unencrypted symlink is
followed.  This can be avoided by checking for unencrypted symlinks first:

        if (!ubifs_crypt_is_encrypted(inode))
                return ui->data;

        if (!dentry)
                return ERR_PTR(-ECHILD);

        err = fscrypt_get_encryption_info(inode);
        if (err)
                return ERR_PTR(err);

> +
> +     pstr.name[err] = '\0';
> +

In 4.9, fscrypt_fname_{disk_to_usr,usr_to_disk} return 0 instead of the output
length, so this will need to be changed to 'pstr.name[pstr.len] = '\0''.

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