Re: [net-ipv4] question about arguments position

[Gustavo A. R. Silva]

Hi Joe,

Quoting Joe Perches <joe@xxxxxxxxxxx>:

> On Thu, 2017-05-04 at 12:46 -0400, David Miller wrote:
> > From: "Gustavo A. R. Silva" <garsilva@xxxxxxxxxxxxxx>
> > Date: Thu, 04 May 2017 11:07:54 -0500
> >
> > > While looking into Coverity ID 1357474 I ran into the following piece
> > > of code at net/ipv4/inet_diag.c:392:
> >
> > Because it's been this way since at least 2005, it doesn't matter if
> > the order is correct or not. What's there is the locked in behavior
> > exposed to userspace and changing it will break things for people.
>
> Adding a few comments around the code about why
> it is this way will help avoid future questions.

In the case of Coverity, I already triaged and documented this issue.  
So people can ignore it in the future.

Regarding the code comments, what about the following patch:

diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
index 3828b3a..7a56641 100644
--- a/net/ipv4/inet_diag.c
+++ b/net/ipv4/inet_diag.c
@@ -389,6 +389,12 @@ static int sk_diag_fill(struct sock *sk, struct  
sk_buff *skb,
                                  nlmsg_flags, unlh, net_admin);
 }

+/*
+ * Ignore the position of the arguments req->id.idiag_dport and
+ * req->id.idiag_sport in both calls to inet_lookup() and inet6_lookup()
+ * functions, once this is a locked in behavior exposed to user space.
+ * Changing this will break things for people.
+ */
 struct sock *inet_diag_find_one_icsk(struct net *net,
                                     struct inet_hashinfo *hashinfo,
                                     const struct inet_diag_req_v2 *req)

Thanks
--
Gustavo A. R. Silva