!2329 ipv4: fix null-deref in ipv4_link_failure

Merge Pull Request from: @ci-robot 
 
PR sync from: Lu Wei <luwei32@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/ROBFO6RW5UGIFBHJTG4V25QPD7TSWVUB/ 
 
https://gitee.com/src-openeuler/kernel/issues/I85DZB 
 
Link:https://gitee.com/openeuler/kernel/pulls/2329

 

Reviewed-by: Yue Haibing <yuehaibing@huawei.com>
Reviewed-by: Liu YongQiang <liuyongqiang13@huawei.com>
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>