netdev - Re: [PATCH net-next v13 3/8] net/sched: flower: Move filter handle initialization earlier

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Message-ID: <CANn89i+Jd6Cy5H0UWS3j+nucGu-e8HP1sqdfoGzS=vGEEGawMw@mail.gmail.com>
Date:   Thu, 23 Feb 2023 11:24:37 +0100
From:   Eric Dumazet <edumazet@...gle.com>
To:     Paul Blakey <paulb@...dia.com>
Cc:     netdev@...r.kernel.org, Saeed Mahameed <saeedm@...dia.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        Oz Shlomo <ozsh@...dia.com>, Jiri Pirko <jiri@...dia.com>,
        Roi Dayan <roid@...dia.com>, Vlad Buslov <vladbu@...dia.com>,
        Ido Schimmel <idosch@...dia.com>,
        Simon Horman <simon.horman@...igine.com>
Subject: Re: [PATCH net-next v13 3/8] net/sched: flower: Move filter handle
 initialization earlier

On Fri, Feb 17, 2023 at 11:36 PM Paul Blakey <paulb@...dia.com> wrote:
>
> To support miss to action during hardware offload the filter's
> handle is needed when setting up the actions (tcf_exts_init()),
> and before offloading.
>
> Move filter handle initialization earlier.
>
> Signed-off-by: Paul Blakey <paulb@...dia.com>
> Reviewed-by: Jiri Pirko <jiri@...dia.com>
> Reviewed-by: Simon Horman <simon.horman@...igine.com>
> Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
> ---

Error path is now potentially crashing because net pointer has not
been initialized.

I plan fixing this issue with the following:

diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index e960a46b05205bb0bca7dc0d21531e4d6a3853e3..475fe222a85566639bac75fc4a95bf649a10357d
100644
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -2200,8 +2200,9 @@ static int fl_change(struct net *net, struct
sk_buff *in_skb,
                fnew->flags = nla_get_u32(tb[TCA_FLOWER_FLAGS]);

                if (!tc_flags_valid(fnew->flags)) {
+                       kfree(fnew);
                        err = -EINVAL;
-                       goto errout;
+                       goto errout_tb;
                }
        }

@@ -2226,8 +2227,10 @@ static int fl_change(struct net *net, struct
sk_buff *in_skb,
                }
                spin_unlock(&tp->lock);

-               if (err)
-                       goto errout;
+               if (err) {
+                       kfree(fnew);
+                       goto errout_tb;
+               }
        }
        fnew->handle = handle;

@@ -2337,7 +2340,6 @@ static int fl_change(struct net *net, struct
sk_buff *in_skb,
        fl_mask_put(head, fnew->mask);
 errout_idr:
        idr_remove(&head->handle_idr, fnew->handle);
-errout:
        __fl_put(fnew);
 errout_tb:
        kfree(tb);