Re: [PATCH RFC 1/6] NFSD: Fix NFSv4 SETATTR's handling of large file sizes

[Dave Chinner <david@fromorbit.com>]

On Fri, Jan 28, 2022 at 01:48:48AM +0000, Chuck Lever III wrote:
> 
> 
> > On Jan 27, 2022, at 7:36 PM, Dave Chinner <david@fromorbit.com> wrote:
> > 
> > On Thu, Jan 27, 2022 at 11:08:31AM -0500, Chuck Lever wrote:
> >> IOW it assumes the caller has already sanity-checked the value.
> > 
> > Every filesystem assumes that the iattr that is passed to ->setattr
> > by notify_change() has been sanity checked and the parameters are
> > within the valid VFS supported ranges, not just XFS. Perhaps this
> > check should be in notify_change, not in the callers?
> 
> My (limited) understanding of the VFS code is that functions at
> the notify_change() level expect that its callers will have
> already sanitized the input -- those callers are largely the
> system call routines. That's why I chose to address this in NFSD.
> 
> Maybe inode_newsize_ok() needs to check for negative size values?

Yeah, that would seem reasonable - the size passed to it is a
loff_t, and it's not checked for overflows/negative values. So if it
checked for offset < 0 if would catch this....

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com