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

[Steve French]

Paulo,
Added your reviewed by to David's patches but wanted to doublecheck
that I didn't apply it to too many of them since I couldn't find one
of your notes

Does this look ok for your RB on all 14 of these - or just the SMB1 one one?

a6fd899da60f (HEAD -> for-next, origin/for-next, origin/HEAD) cifs:
Remove dead function prototypes
1b7270c879f5 smb: server: defer the initial recv completion logic to
smb_direct_negotiate_recv_work()
9d095775a0cb smb: server: initialize recv_io->cqe.done = recv_done just once
667246dbce2d smb: smbdirect: introduce smbdirect_socket.connect.{lock,work}
2b4e375e4006 cifs: Do some preparation prior to organising the
function declarations
c3bdaf3afd87 cifs: Add a tracepoint to log EIO errors
cb416ff96b83 cifs: Don't need state locking in smb2_get_mid_entry()
a64fa1835237 cifs: Remove the server pointer from smb_message
960cd2e1e28a cifs: Fix specification of function pointers
2fdd780130d1 cifs: Replace SendReceiveBlockingLock() with
SendReceive() plus flags
bb8172e800b3 cifs: Clean up some places where an extra kvec[] was
required for rfc1002
41daa3d4a238 cifs: Make smb1's SendReceive() wrap cifs_send_recv()
3ed72b50d276 cifs: Remove the RFC1002 header from smb_hdr
271b1138e8b4 cifs: Fix handling of a beyond-EOF DIO/unbuffered read over SMB1

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?
>
> Thanks.
>


--
Thanks,

Steve