i40e: Fix use-after-free in i40e_client_subtask()

stable inclusion
from stable-v4.19.191
commit c1322eaeb8af0d8985b5cc5fa759140fa0e57b84
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5RZPX
CVE: NA

--------------------------------

[ Upstream commit 38318f23 ]

Currently the call to i40e_client_del_instance frees the object
pf->cinst, however pf->cinst->lan_info is being accessed after
the free. Fix this by adding the missing return.

Addresses-Coverity: ("Read from pointer after free")
Fixes: 7b0b1a6d ("i40e: Disable iWARP VSI PETCP_ENA flag on netdev down events")
Signed-off-by: NYunjian Wang <wangyunjian@huawei.com>
Signed-off-by: NTony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Ntangbin <tangbin_yewu@cmss.chinamobile.com>

drivers/net/ethernet/intel/i40e/i40e_client.c

@@ -377,6 +377,7 @@ void i40e_client_subtask(struct i40e_pf *pf)
 				clear_bit(__I40E_CLIENT_INSTANCE_OPENED,
 					  &cdev->state);
 				i40e_client_del_instance(pf);
+				return;
 			}
 		}
 	}