net: hns3: fix use-after-free bug in hclgevf_send_mbx_msg

jira VULN-63094
cve CVE-2021-47596
commit-author Jie Wang <[email protected]>
commit 27cbf64

Currently, the hns3_remove function firstly uninstall client instance,
and then uninstall acceletion engine device. The netdevice is freed in
client instance uninstall process, but acceletion engine device uninstall
process still use it to trace runtime information. This causes a use after
free problem.

So fixes it by check the instance register state to avoid use after free.

Fixes: d835524 ("net: hns3: add trace event support for PF/VF mailbox")
	Signed-off-by: Jie Wang <[email protected]>
	Signed-off-by: Guangbin Huang <[email protected]>
	Signed-off-by: David S. Miller <[email protected]>
(cherry picked from commit 27cbf64)
	Signed-off-by: Brett Mastbergen <[email protected]>

Author: bmastbergen

drivers/net/ethernet/hisilicon/hns3/hns3vf/hclgevf_mbx.c

@@ -114,7 +114,8 @@ int hclgevf_send_mbx_msg(struct hclgevf_dev *hdev,
 
 	memcpy(&req->msg, send_msg, sizeof(struct hclge_vf_to_pf_msg));
 
-	trace_hclge_vf_mbx_send(hdev, req);
+	if (test_bit(HCLGEVF_STATE_NIC_REGISTERED, &hdev->state))
+		trace_hclge_vf_mbx_send(hdev, req);
 
 	/* synchronous send */
 	if (need_resp) {