Re: [PATCH v1] i40e: Lock VF cloud filter list operations

[Jacob Keller <jacob.e.keller@intel.com>]

On 10/29/2026 1:01 AM, Loktionov, Aleksandr wrote:
> 
> 
>> -----Original Message-----
>> From: Binbin Deng <18983559317@163.com>
>> Sent: Tuesday, October 20, 2026 4:59 AM
>> To: Nguyen, Anthony L <anthony.l.nguyen@intel.com>; Kitszel, Przemyslaw
>> <przemyslaw.kitszel@intel.com>; andrew+netdev@lunn.ch;
>> davem@davemloft.net; edumazet@google.com; kuba@kernel.org;
>> pabeni@redhat.com
>> Cc: intel-wired-lan@lists.osuosl.org; netdev@vger.kernel.org; linux-
>> kernel@vger.kernel.org; Binbin Deng <18983559317@163.com>
>> Subject: [PATCH v1] i40e: Lock VF cloud filter list operations
>>
>> A VF's cloud-filter hlist is modified by the virtchnl add and delete
>> handlers and by i40e_del_all_cloud_filters(), which runs when ADq is
>> disabled or when the VF loses trusted status.  These paths do not share
>> a lock.  In particular, the PF's async VF-message handler can process
>> VIRTCHNL_OP_DEL_CLOUD_FILTER while host-side ndo_set_vf_trust() removes
>> every cloud filter for that VF.
>>
>> The race is reachable from a guest by issuing cloud-filter virtchnl
>> requests while the host revokes VF trust or disables ADq.  The VF-
>> message handler can traverse nodes that the bulk-delete path has already
>> freed, or both paths can remove the same node.  The result can be a
>> KASAN use-after-free, hlist corruption, incorrect filter accounting, or
>> a panic.
>> The virtchnl operation-pending bit does not serialize this host-side
>> trust path.
>>
>> Serialize cloud-filter control operations with a mutex.  Hold it across
>> the firmware add or delete, hlist update, and free, so bulk deletion and
>> individual add/delete operations cannot observe a partially removed
>> list.
>> The lock is file-local and slow-path only.
>>
>> Found during a static-analysis-assisted audit: candidate sites were
>> surfaced by a Coccinelle rule, and the reader/writer paths were
>> confirmed by LLM-assisted (GLM-5.3) code inspection. Due to a lack of
>> hardware infrastructureThe issue was not observed at runtime.
>> It is identified by code inspection only.
>>
>> Fixes: e284fc280473 ("i40e: Add and delete cloud filter")
>> Assisted-by: GLM-5.3 coccinelle
>> Signed-off-by: Binbin Deng <18983559317@163.com>
>> ---
>>  drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c | 10 ++++++++++
>>  1 file changed, 10 insertions(+)
>>
>> diff --git a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
>> b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
>> index a26c3d47ec15..f73a710f42f1 100644
>> --- a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
>> +++ b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
>> @@ -3740,6 +3740,8 @@ static struct i40e_vsi
>> *i40e_find_vsi_from_seid(struct i40e_vf *vf, u16 seid)
>>   *
>>   * This function deletes all cloud filters
>>   **/
>> +static DEFINE_MUTEX(i40e_vf_cloud_filter_lock);
>> +
>>  static void i40e_del_all_cloud_filters(struct i40e_vf *vf)  {
>>  	struct i40e_cloud_filter *cfilter = NULL; @@ -3748,6 +3750,7 @@
>> static void i40e_del_all_cloud_filters(struct i40e_vf *vf)
>>  	struct hlist_node *node;
>>  	int ret;
>>
>> +	mutex_lock(&i40e_vf_cloud_filter_lock);
>>  	hlist_for_each_entry_safe(cfilter, node,
>>  				  &vf->cloud_filter_list, cloud_node) {
>>  		vsi = i40e_find_vsi_from_seid(vf, cfilter->seid); @@ -
>> 3773,6 +3776,7 @@ static void i40e_del_all_cloud_filters(struct i40e_vf
>> *vf)
>>  		kfree(cfilter);
>>  		vf->num_cloud_filters--;
>>  	}
>> +	mutex_unlock(&i40e_vf_cloud_filter_lock);
>>  }
>>
>>  /**
>> @@ -3856,6 +3860,7 @@ static int i40e_vc_del_cloud_filter(struct i40e_vf
>> *vf, u8 *msg)
>>  	}
>>
>>  	/* get the vsi to which the tc belongs to */
>> +	mutex_lock(&i40e_vf_cloud_filter_lock);
>>  	vsi = pf->vsi[vf->ch[vcf->action_meta].vsi_idx];
>>  	cfilter.seid = vsi->seid;
>>  	cfilter.flags = vcf->field_flags;
>> @@ -3870,6 +3875,7 @@ static int i40e_vc_del_cloud_filter(struct i40e_vf
>> *vf, u8 *msg)
>>  			"VF %d: Failed to delete cloud filter, err %pe
>> aq_err %s\n",
>>  			vf->vf_id, ERR_PTR(ret),
>>  			libie_aq_str(pf->hw.aq.asq_last_status));
>> +		mutex_unlock(&i40e_vf_cloud_filter_lock);
>>  		goto err;
>>  	}
>>
>> @@ -3901,6 +3907,7 @@ static int i40e_vc_del_cloud_filter(struct i40e_vf
>> *vf, u8 *msg)
>>  		kfree(cf);
>>  		vf->num_cloud_filters--;
>>  	}
>> +	mutex_unlock(&i40e_vf_cloud_filter_lock);
>>
>>  err:
>>  	return i40e_vc_send_resp_to_vf(vf, VIRTCHNL_OP_DEL_CLOUD_FILTER,
>> @@ -4002,6 +4009,7 @@ static int i40e_vc_add_cloud_filter(struct i40e_vf
>> *vf, u8 *msg)
>>  	}
>>
>>  	/* get the VSI to which the TC belongs to */
>> +	mutex_lock(&i40e_vf_cloud_filter_lock);
>>  	vsi = pf->vsi[vf->ch[vcf->action_meta].vsi_idx];
>>  	cfilter->seid = vsi->seid;
>>  	cfilter->flags = vcf->field_flags;
>> @@ -4016,6 +4024,7 @@ static int i40e_vc_add_cloud_filter(struct i40e_vf
>> *vf, u8 *msg)
>>  			"VF %d: Failed to add cloud filter, err %pe aq_err
>> %s\n",
>>  			vf->vf_id, ERR_PTR(aq_ret),
>>  			libie_aq_str(pf->hw.aq.asq_last_status));
>> +		mutex_unlock(&i40e_vf_cloud_filter_lock);
>>  		goto err_free;
>>  	}
>>
>> @@ -4024,6 +4033,7 @@ static int i40e_vc_add_cloud_filter(struct i40e_vf
>> *vf, u8 *msg)
>>  	/* release the pointer passing it to the collection */
>>  	cfilter = NULL;
>>  	vf->num_cloud_filters++;
>> +	mutex_unlock(&i40e_vf_cloud_filter_lock);
>>  err_free:
>>  	kfree(cfilter);
>>  err_out:
>> --
>> 2.43.0
> 
> I'm afraid one more global lock shared among all cards on server will make things worse.
> @Jakub Kicinski can you comment?

Agreed. Even if the race is real (it hasn't been confirmed on actual
hardware), this is not the right fix. The driver should maintain a lock
on the relevant data structure and this is clearly a hack of a fix.

I'm going to reject this from IWL patchwork. Can someone from the FNIC
team make a note about this potential issue so we can investigate and
develop a proper fix?

Thanks,
Jake