!1762 xen/netback: Fix buffer overrun triggered by unusual packet

Merge Pull Request from: @ci-robot 
 
PR sync from: Zhengchao Shao <shaozhengchao@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/Y2HCYNOFJA5N4QNNUNQKEHGLDOAVGM25/ 
 
https://gitee.com/src-openeuler/kernel/issues/I7RQ63 
 
Link:https://gitee.com/openeuler/kernel/pulls/1762

 

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