[PATCH net v2] iavf: validate num_vsis in VIRTCHNL_OP_GET_VF_RESOURCES response

[Junrui Luo]

The VF allocates a fixed-size buffer for IAVF_MAX_VF_VSI (3) VSI
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, or the received
message is shorter than num_vsis claims leads to out-of-bounds accesses
on the vsi_res[] array.

Clamp num_vsis based on the actual bytes copied from the PF response.

Fixes: 5eae00c57f5e ("i40evf: main driver core")
Reported-by: Yuhao Jiang <danisjiang@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Junrui Luo <moonafterrain@xxxxxxxxxxx>
---
Changes in v2:
- Clamp num_vsis based on actual received message length instead of
IAVF_MAX_VF_VSI suggested by Przemek
- Link to v1: https://lore.kernel.org/r/SYBPR01MB7881AF11C45AEDC0D4CA89C1AF062@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
---
 drivers/net/ethernet/intel/iavf/iavf_virtchnl.c | 26 ++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c b/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c
index a52c100dcbc5..1f9a2fc70084 100644
--- a/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c
+++ b/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c
@@ -248,12 +248,28 @@ int iavf_send_vf_ptp_caps_msg(struct iavf_adapter *adapter)
 /**
  * iavf_validate_num_queues
  * @adapter: adapter structure
+ * @msglen: length of the received VF resource message
  *
- * Validate that the number of queues the PF has sent in
- * VIRTCHNL_OP_GET_VF_RESOURCES is not larger than the VF can handle.
+ * Validate the VIRTCHNL_OP_GET_VF_RESOURCES response from the PF. Ensure
+ * num_vsis does not exceed what the message length can cover, and cap
+ * num_queue_pairs to the VF maximum.
  **/
-static void iavf_validate_num_queues(struct iavf_adapter *adapter)
+static void iavf_validate_num_queues(struct iavf_adapter *adapter, u16 msglen)
 {
+	u16 max_vsis;
+
+	if (msglen < sizeof(struct virtchnl_vf_resource))
+		max_vsis = 0;
+	else
+		max_vsis = (msglen - sizeof(struct virtchnl_vf_resource)) /
+			   sizeof(struct virtchnl_vsi_resource);
+
+	if (adapter->vf_res->num_vsis > max_vsis) {
+		dev_info(&adapter->pdev->dev, "Received %d VSIs, but message can only cover %d\n",
+			 adapter->vf_res->num_vsis, max_vsis);
+		adapter->vf_res->num_vsis = max_vsis;
+	}
+
 	if (adapter->vf_res->num_queue_pairs > IAVF_MAX_REQ_QUEUES) {
 		struct virtchnl_vsi_resource *vsi_res;
 		int i;
@@ -300,7 +316,7 @@ int iavf_get_vf_config(struct iavf_adapter *adapter)
 	 * we aren't getting too many queues
 	 */
 	if (!err)
-		iavf_validate_num_queues(adapter);
+		iavf_validate_num_queues(adapter, min(event.msg_len, len));
 	iavf_vf_parse_hw_config(hw, adapter->vf_res);
 
 	kfree(event.msg_buf);
@@ -2609,7 +2625,7 @@ void iavf_virtchnl_completion(struct iavf_adapter *adapter,
 		u16 len = IAVF_VIRTCHNL_VF_RESOURCE_SIZE;
 
 		memcpy(adapter->vf_res, msg, min(msglen, len));
-		iavf_validate_num_queues(adapter);
+		iavf_validate_num_queues(adapter, min(msglen, len));
 		iavf_vf_parse_hw_config(&adapter->hw, adapter->vf_res);
 		if (is_zero_ether_addr(adapter->hw.mac.addr)) {
 			/* restore current mac address */

---
base-commit: 7aaa8047eafd0bd628065b15757d9b48c5f9c07d
change-id: 20260514-fixes-a6c4176c0c6a

Best regards,
-- 
Junrui Luo <moonafterrain@xxxxxxxxxxx>