Re: [PATCH] mm: adjust max read count in generic_file_buffered_read()

[Jan Kara]

On Fri 20-07-18 16:14:29, Andrew Morton wrote:
> On Thu, 19 Jul 2018 10:58:12 +0200 Jan Kara <jack@xxxxxxx> wrote:
> 
> > On Thu 19-07-18 16:17:26, Chengguang Xu wrote:
> > > When we try to truncate read count in generic_file_buffered_read(),
> > > should deliver (sb->s_maxbytes - offset) as maximum count not
> > > sb->s_maxbytes itself.
> > > 
> > > Signed-off-by: Chengguang Xu <cgxu519@xxxxxxx>
> > 
> > Looks good to me. You can add:
> > 
> > Reviewed-by: Jan Kara <jack@xxxxxxx>
> 
> Yup.
> 
> What are the runtime effects of this bug?

Good question. I think ->readpage() could be called for index beyond
maximum file size supported by the filesystem leading to weird filesystem
behavior due to overflows in internal calculations.

								Honza
-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR