Re: [PATCH v1 01/13] fs: Don't copy beyond the end of the file

[bfields@fieldses.org (J. Bruce Fields)]

On Fri, Oct 19, 2018 at 11:28:53AM -0400, Olga Kornievskaia wrote:
> From: Anna Schumaker <Anna.Schumaker@Netapp.com>

I have some idea we've had some discussion about this before, but if so
I've forgotten the conclusion.  Could we have more of a changelog?:

	- isn't there a race condition, or is there something preventing
	  the file size from changing here?
	- why are we doing this?  Does this change the behavior of
	  copy_file_range()?

--b.

> 
> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
> ---
>  fs/read_write.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/fs/read_write.c b/fs/read_write.c
> index 39b4a21..c60790f 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -1570,6 +1570,9 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
>  	if (unlikely(ret))
>  		return ret;
>  
> +	if (pos_in >= i_size_read(inode_in))
> +		return -EINVAL;
> +
>  	if (!(file_in->f_mode & FMODE_READ) ||
>  	    !(file_out->f_mode & FMODE_WRITE) ||
>  	    (file_out->f_flags & O_APPEND))
> -- 
> 1.8.3.1