Re: [PATCH] cifs: Fix handling of a beyond-EOF DIO/unbuffered read over SMB1

[Steve French]

On Wed, Dec 3, 2025 at 12:03 PM Paulo Alcantara <pc@xxxxxxxxxxxxx> wrote:
>
> David Howells <dhowells@xxxxxxxxxx> writes:
>
> >
> > If a DIO read or an unbuffered read request extends beyond the EOF, the
> > server will return a short read and a status code indicating that EOF was
> > hit, which gets translated to -ENODATA.  Note that the client does not cap
> > the request at i_size, but asks for the amount requested in case there's a
> > race on the server with a third party.
> >
> > Now, on the client side, the request will get split into multiple
> > subrequests if rsize is smaller than the full request size.  A subrequest
> > that starts before or at the EOF and returns short data up to the EOF will
> > be correctly handled, with the NETFS_SREQ_HIT_EOF flag being set,
> > indicating to netfslib that we can't read more.
> >
> > If a subrequest, however, starts after the EOF and not at it, HIT_EOF will
> > not be flagged, its error will be set to -ENODATA and it will be abandoned.
> > This will cause the request as a whole to fail with -ENODATA.
> >
> > Fix this by setting NETFS_SREQ_HIT_EOF on any subrequest that lies beyond
> > the EOF marker.
> >
> > This can be reproduced by mounting with "cache=none,sign,vers=1.0" and
> > doing a read of a file that's significantly bigger than the size of the
> > file (e.g. attempting to read 64KiB from a 16KiB file).
> >
> > Fixes: a68c74865f51 ("cifs: Fix SMB1 readv/writev callback in the same way as SMB2/3")
> > Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
> > cc: Steve French <sfrench@xxxxxxxxx>
> > cc: Paulo Alcantara <pc@xxxxxxxxxxxxx>
> > cc: Shyam Prasad N <sprasad@xxxxxxxxxxxxx>
> > cc: linux-cifs@xxxxxxxxxxxxxxx
> > cc: netfs@xxxxxxxxxxxxxxx
> > cc: linux-fsdevel@xxxxxxxxxxxxxxx
>
> Reviewed-by: Paulo Alcantara (Red Hat) <pc@xxxxxxxxxxxxx>
>
> Dave, looks like we're missing a similar fix for smb2_readv_callback()
> as well.
>
> Can you handle it?

Any luck reproducing it for smb2/smb3/smb3.1.1?

-- 
Thanks,

Steve