Re: [PATCH net] iavf: validate num_vsis in VIRTCHNL_OP_GET_VF_RESOURCES response

[Przemek Kitszel <przemyslaw.kitszel@intel.com>]

On 5/13/26 10:51, Junrui Luo wrote:
> The VF allocates a fixed-size buffer for IAVF_MAX_VF_VSI (3) VSI

this is the MAX that iavf sends to PF (and only usage of the variable)

> entries when processing a VIRTCHNL_OP_GET_VF_RESOURCES response from
> the PF. However, num_vsis from the PF response is used unchecked as
> the loop bound when iterating over vsi_res[] in multiple functions.
> 
> A PF sending num_vsis greater than IAVF_MAX_VF_VSI leads to
> out-of-bounds accesses on the vsi_res[] array.

this array is part of the same message from PF as the counter

Thank you for reaching out,
as is, this is not a fix
if you want to add some hardening for iavf receiving side,
you could add some checks that passed msg lengths cover whole
messages (when accounted for FAM)

> 
> Clamp num_vsis to IAVF_MAX_VF_VSI in iavf_validate_num_queues(),
> following the same pattern already used for num_queue_pairs.
> 
> Fixes: 5eae00c57f5e ("i40evf: main driver core")
> Reported-by: Yuhao Jiang <danisjiang@gmail.com>
> Cc: stable@vger.kernel.org
> Signed-off-by: Junrui Luo <moonafterrain@outlook.com>
> ---
>   drivers/net/ethernet/intel/iavf/iavf_virtchnl.c | 6 ++++++
>   1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c b/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c
> index a52c100dcbc5..2ebfb65a6f3b 100644
> --- a/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c
> +++ b/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c
> @@ -254,6 +254,12 @@ int iavf_send_vf_ptp_caps_msg(struct iavf_adapter *adapter)
>    **/
>   static void iavf_validate_num_queues(struct iavf_adapter *adapter)
>   {
> +	if (adapter->vf_res->num_vsis > IAVF_MAX_VF_VSI) {
> +		dev_info(&adapter->pdev->dev, "Received %d VSIs, but can only have a max of %d\n",
> +			 adapter->vf_res->num_vsis, IAVF_MAX_VF_VSI);
> +		adapter->vf_res->num_vsis = IAVF_MAX_VF_VSI;
> +	}
> +
>   	if (adapter->vf_res->num_queue_pairs > IAVF_MAX_REQ_QUEUES) {
>   		struct virtchnl_vsi_resource *vsi_res;
>   		int i;
> 
> ---
> base-commit: 7aaa8047eafd0bd628065b15757d9b48c5f9c07d
> change-id: 20260513-fixes-26ec29fa50a5
> 
> Best regards,