Re: [PATCH] ntfs3: fix info-leak in ntfs_rename()

[Al Viro <viro@zeniv.linux.org.uk>]

On Tue, Jun 09, 2026 at 03:36:18PM +0300, Dmitry Antipov wrote:
> In 'ntfs_rename()', buffer passed to 'fill_name_de()' should
> be allocated with 'kzalloc()' to avoid exposing contents of
> an uninitialized kernel memory via 'copy_to_user_iter()'.
> 
> Reported-by: syzbot+905d785c4923bea2c1db@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=905d785c4923bea2c1db
> Fixes: ca2a04e84af7 ("ntfs: ->d_compare() must not block")
> Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
> ---
>  fs/ntfs3/namei.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/ntfs3/namei.c b/fs/ntfs3/namei.c
> index b2af8f695e60..74fe002214f3 100644
> --- a/fs/ntfs3/namei.c
> +++ b/fs/ntfs3/namei.c
> @@ -303,7 +303,7 @@ static int ntfs_rename(struct mnt_idmap *idmap, struct inode *dir,
>  			return err;
>  	}
>  
> -	de = kmalloc(PATH_MAX, GFP_KERNEL);
> +	de = kzalloc(PATH_MAX, GFP_KERNEL);
>  	if (!de)
>  		return -ENOMEM;

Could you please elaborate the way by which the contents of that
object would have managed to reach copy_to_user_iter()?
While we are at it, which userland addresses would rename()
want to write into?