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

> 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 <feliu@redhat.com>
> Signed-off-by: Ivan Vecera <ivecera@redhat.com>
> ---
> 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
>
> _______________________________________________
> Intel-wired-lan mailing list
> Intel-wired-lan@osuosl.org
> https://lists.osuosl.org/mailman/listinfo/intel-wired-lan

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