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SubjectRe: [PATCH v2,net-next 1/2] ip_gre: fix parsing gre header in ipgre_err
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> On 2018年9月14日, at 上午1:58, David Miller <davem@davemloft.net> wrote:
>
> From: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
> Date: Wed, 12 Sep 2018 17:21:21 +0800
>
>> @@ -86,7 +86,7 @@ int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,
>>
>> options = (__be32 *)(greh + 1);
>> if (greh->flags & GRE_CSUM) {
>> - if (skb_checksum_simple_validate(skb)) {
>> + if (csum_err && skb_checksum_simple_validate(skb)) {
>> *csum_err = true;
>> return -EINVAL;
>> }
>
> You want to ignore csum errors, but you do not want to elide the side
> effects of the skb_checksum_simple_validate() call which are to set
> skb->csum_valid and skb->csum.
>
> Therefore, the skb_checksum_simple_validate() call still needs to be
> performed. We just wont return -EINVAL in the NULL csum_err case.
>
>

How about doing like this:

--- a/net/ipv4/gre_demux.c
+++ b/net/ipv4/gre_demux.c
@@ -86,13 +86,14 @@ int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,

options = (__be32 *)(greh + 1);
if (greh->flags & GRE_CSUM) {
- if (skb_checksum_simple_validate(skb)) {
+ if (!skb_checksum_simple_validate(skb)) {
+ skb_checksum_try_convert(skb, IPPROTO_GRE, 0,
+ null_compute_pseudo);
+ } else if (csum_err) {
*csum_err = true;
return -EINVAL;
}

- skb_checksum_try_convert(skb, IPPROTO_GRE, 0,
- null_compute_pseudo);

Thanks for reviewing.


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