Subject: Re: [Intel-wired-lan] [PATCH net] ice: Protect vf_state check by cfg_lock in ice_vc_process_vf_msg()

From: Maciej Fijalkowski <[email-masked]>
Date: Fri, 15 Apr 2022 13:57:37 +0200

On Fri, Apr 15, 2022 at 01:55:10PM +0200, Maciej Fijalkowski wrote:
> On Wed, Apr 13, 2022 at 09:22:59AM +0200, Ivan Vecera wrote:
> > Previous patch labelled "ice: Fix incorrect locking in
> > ice_vc_process_vf_msg()"  fixed an issue with ignored messages
> 
> tiny tiny nit: double space after "
> Also, has mentioned patch landed onto some tree so that we could provide
> SHA-1 of it? If not, then maybe squashing this one with the mentioned one
> would make sense?

Again, Brett's Intel address is bouncing, so:
CC: Brett Creeley <[email-masked]>

> 
> > sent by VF driver but a small race window still left.
> > 
> > Recently caught trace during 'ip link set ... vf 0 vlan ...' operation:
> > 
> > [ 7332.995625] ice 0000:3b:00.0: Clearing port VLAN on VF 0
> > [ 7333.001023] iavf 0000:3b:01.0: Reset indication received from the PF
> > [ 7333.007391] iavf 0000:3b:01.0: Scheduling reset task
> > [ 7333.059575] iavf 0000:3b:01.0: PF returned error -5 (IAVF_ERR_PARAM) to our request 3
> > [ 7333.059626] ice 0000:3b:00.0: Invalid message from VF 0, opcode 3, len 4, error -1
> > 
> > Setting of VLAN for VF causes a reset of the affected VF using
> > ice_reset_vf() function that runs with cfg_lock taken:
> > 
> > 1. ice_notify_vf_reset() informs IAVF driver that reset is needed and
> >    IAVF schedules its own reset procedure
> > 2. Bit ICE_VF_STATE_DIS is set in vf->vf_state
> > 3. Misc initialization steps
> > 4. ice_sriov_post_vsi_rebuild() -> ice_vf_set_initialized() and that
> >    clears ICE_VF_STATE_DIS in vf->vf_state
> > 
> > Step 3 is mentioned race window because IAVF reset procedure runs in
> > parallel and one of its step is sending of VIRTCHNL_OP_GET_VF_RESOURCES
> > message (opcode==3). This message is handled in ice_vc_process_vf_msg()
> > and if it is received during the mentioned race window then it's
> > marked as invalid and error is returned to VF driver.
> > 
> > Protect vf_state check in ice_vc_process_vf_msg() by cfg_lock to avoid
> > this race condition.
> > 
> > Fixes: e6ba5273d4ed ("ice: Fix race conditions between virtchnl handling and VF ndo ops")
> > Tested-by: Fei Liu <[email-masked]>
> > Signed-off-by: Ivan Vecera <[email-masked]>
> > ---
> >  drivers/net/ethernet/intel/ice/ice_virtchnl.c | 38 +++++++++----------
> >  1 file changed, 17 insertions(+), 21 deletions(-)
> > 
> > diff --git a/drivers/net/ethernet/intel/ice/ice_virtchnl.c b/drivers/net/ethernet/intel/ice/ice_virtchnl.c
> > index 5612c032f15a..553287a75b50 100644
> > --- a/drivers/net/ethernet/intel/ice/ice_virtchnl.c
> > +++ b/drivers/net/ethernet/intel/ice/ice_virtchnl.c
> > @@ -3625,44 +3625,39 @@ void ice_vc_process_vf_msg(struct ice_pf *pf, struct ice_rq_event_info *event)
> >  		return;
> >  	}
> >  
> > +	mutex_lock(&vf->cfg_lock);
> > +
> >  	/* Check if VF is disabled. */
> >  	if (test_bit(ICE_VF_STATE_DIS, vf->vf_states)) {
> >  		err = -EPERM;
> > -		goto error_handler;
> > -	}
> > -
> > -	ops = vf->virtchnl_ops;
> > -
> > -	/* Perform basic checks on the msg */
> > -	err = virtchnl_vc_validate_vf_msg(&vf->vf_ver, v_opcode, msg, msglen);
> > -	if (err) {
> > -		if (err == VIRTCHNL_STATUS_ERR_PARAM)
> > -			err = -EPERM;
> > -		else
> > -			err = -EINVAL;
> > +	} else {
> > +		/* Perform basic checks on the msg */
> > +		err = virtchnl_vc_validate_vf_msg(&vf->vf_ver, v_opcode, msg,
> > +						  msglen);
> > +		if (err) {
> > +			if (err == VIRTCHNL_STATUS_ERR_PARAM)
> > +				err = -EPERM;
> > +			else
> > +				err = -EINVAL;
> > +		}
> 
> The chunk above feels a bit like unnecessary churn, no?
> Couldn't this patch be simply focused only on extending critical section?
> 
> >  	}
> > -
> > -error_handler:
> >  	if (err) {
> >  		ice_vc_send_msg_to_vf(vf, v_opcode, VIRTCHNL_STATUS_ERR_PARAM,
> >  				      NULL, 0);
> >  		dev_err(dev, "Invalid message from VF %d, opcode %d, len %d, error %d\n",
> >  			vf_id, v_opcode, msglen, err);
> > -		ice_put_vf(vf);
> > -		return;
> > +		goto finish;
> >  	}
> >  
> > -	mutex_lock(&vf->cfg_lock);
> > -
> >  	if (!ice_vc_is_opcode_allowed(vf, v_opcode)) {
> >  		ice_vc_send_msg_to_vf(vf, v_opcode,
> >  				      VIRTCHNL_STATUS_ERR_NOT_SUPPORTED, NULL,
> >  				      0);
> > -		mutex_unlock(&vf->cfg_lock);
> > -		ice_put_vf(vf);
> > -		return;
> > +		goto finish;
> >  	}
> >  
> > +	ops = vf->virtchnl_ops;
> > +
> >  	switch (v_opcode) {
> >  	case VIRTCHNL_OP_VERSION:
> >  		err = ops->get_ver_msg(vf, msg);
> > @@ -3773,6 +3768,7 @@ void ice_vc_process_vf_msg(struct ice_pf *pf, struct ice_rq_event_info *event)
> >  			 vf_id, v_opcode, err);
> >  	}
> >  
> > +finish:
> >  	mutex_unlock(&vf->cfg_lock);
> >  	ice_put_vf(vf);
> >  }
> > -- 
> > 2.35.1
> > 
> > _______________________________________________
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> > [email-masked]
> > https://lists.osuosl.org/mailman/listinfo/intel-wired-lan