# Re: \[Patch\] Fixing order of trinary operator when assigning the ifindex in XFRM Decode Session

- From: David Ahern \<hidden\>
- Date: 2017-01-12 20:28:55 
- List: netdev
- Page: https://ratatoskr.run/netdev/2017/01/11040581
- Thread: https://ratatoskr.run/netdev/2017/01/11040581/t.md

```text
Hi Carlos:

patches sent to netdev should be plain text only. Using git send-email would be best.

Also, the Subject line should start with the area affected (e.g., net: xfrm:) and really should be a bit shorter. e.g., something like this:

[PATCH] net: xfrm: fix flow oif in decode_session


On 1/12/17 1:01 PM, Chacon, Carlos A wrote:
> 
> Author: Carlos Chacon [ref]
> Date:   Thu Jan 12 11:42:32 2017 -0800
> 
>     Fixing order of trinary operator when assigning the ifindex in XFRM Decode Session
> 
>     For xfrm4_policy.c:_decode_session4 and xfrm6_policy.c:_decode_session6 the line
>         fl4->flowi4_oif = reverse ? skb->skb_iif : oif;
>         fl6->flowi6_oif = reverse ? skb->skb_iif : oif;
>     is assigning the incorrect oif to the flow_oif. It should read:
>         reverse ? oif : skb->skb_iif;
>     The "reverse" variable is defined in  net/xfrm/xfrm_policy.c:__xfrm_policy_check
>     when it checks if the dir is above the XFRM_POLICY_MASK if this returns false
>     it reverses the ifindex, but it should only reverse if it returns true.

The above explanation suggests the reverse flag in __xfrm_policy_check should be fixed. Can you check that and maybe __xfrm_policy_check2 as well?
```