Re: [PATCH 03/17] Drivers: hv: kvp: Cleanup error handling in KVP

Ben Hutchings
2012-07-25T14:47:35Z

On Wed, Jul 25, 2012 at 02:10:05PM +0000, KY Srinivasan wrote:
>
>
> > -----Original Message-----
> > From: Ben Hutchings [mailto:ben@decadent.org.uk]
> > Sent: Tuesday, July 24, 2012 9:11 PM
> > To: KY Srinivasan
> > Cc: gregkh@linuxfoundation.org; linux-kernel@vger.kernel.org;
> > devel@linuxdriverproject.org; virtualization@lists.osdl.org; olaf@aepfle.de;
> > apw@canonical.com; netdev@vger.kernel.org
> > Subject: Re: [PATCH 03/17] Drivers: hv: kvp: Cleanup error handling in KVP
> >
> > On Tue, 2012-07-24 at 09:01 -0700, K. Y. Srinivasan wrote:
> > > In preparation to implementing IP injection, cleanup the way we propagate
> > > and handle errors both in the driver as well as in the user level daemon.
> > >
> > > Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
> > > Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
> > > ---
> > > drivers/hv/hv_kvp.c | 112 +++++++++++++++++++++++++++++++++++++-
> > --------
> > > include/linux/hyperv.h | 17 +++++---
> > > tools/hv/hv_kvp_daemon.c | 70 +++++++++++++++-------------
> > > 3 files changed, 138 insertions(+), 61 deletions(-)
> > >
> > > diff --git a/drivers/hv/hv_kvp.c b/drivers/hv/hv_kvp.c
> > > index 0012eed..9b7fc4a 100644
> > > --- a/drivers/hv/hv_kvp.c
> > > +++ b/drivers/hv/hv_kvp.c
> > [...]
> > > @@ -109,27 +154,52 @@ kvp_cn_callback(struct cn_msg *msg, struct
> > netlink_skb_parms *nsp)
> > > {
> > > struct hv_kvp_msg *message;
> > > struct hv_kvp_msg_enumerate *data;
> > > + int error = 0;
> > >
> > > message = (struct hv_kvp_msg *)msg->data;
> > > - switch (message->kvp_hdr.operation) {
> > > +
> > > + /*
> > > + * If we are negotiating the version information
> > > + * with the daemon; handle that first.
> > > + */
> > > +
> > > + if (in_hand_shake) {
> > > + if (kvp_handle_handshake(message))
> > > + in_hand_shake = false;
> > > + return;
> > > + }
> > > +
> > > + /*
> > > + * Based on the version of the daemon, we propagate errors from the
> > > + * daemon differently.
> > > + */
> > > +
> > > + data = &message->body.kvp_enum_data;
> > > +
> > > + switch (dm_reg_value) {
> > > case KVP_OP_REGISTER:
> > > - pr_info("KVP: user-mode registering done.\n");
> > > - kvp_register();
> > > - kvp_transaction.active = false;
> > > - hv_kvp_onchannelcallback(kvp_transaction.kvp_context);
> > > + /*
> > > + * Null string is used to pass back error condition.
> > > + */
> > > + if (!strlen(data->data.key))
> >
> > Do we know that the key is null-terminated here? Shouldn't we just
> > check whether data->data.key[0] == 0?
>
> Yes, currently we do return null string to indicate error.
[...]

So the kernel should assume userland input is always valid?

Ben.

--
Ben Hutchings
We get into the habit of living before acquiring the habit of thinking.
- Albert Camus