Re: [PATCH 09/14] net: sched: don't release reference on action overwrite

Vlad Buslov
2018-05-16T07:47:59Z

On Wed 16 May 2018 at 07:43, Jiri Pirko <jiri@resnulli.us> wrote:
> Mon, May 14, 2018 at 04:27:10PM CEST, vladbu@mellanox.com wrote:
>>Return from action init function with reference to action taken,
>>even when overwriting existing action.
>>
>>Action init API initializes its fourth argument (pointer to pointer to
>>tc action) to either existing action with same index or newly created
>>action. In case of existing index(and bind argument is zero), init
>>function returns without incrementing action reference counter. Caller
>>of action init then proceeds working with action without actually
>>holding reference to it. This means that action could be deleted
>>concurrently. To prevent such scenario this patch changes action init
>
> Be imperative to the codebase in the patch description.
>
>
>>behavior to always take reference to action before returning
>>successfully.
>
> Where's the balance? Who does the release instead? I'm probably missing
> something.

I've resplit these patches for V2 to always do take/release in same
patch.

>
>>
>>Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
>>---
>> net/sched/act_bpf.c | 8 ++++----
>> net/sched/act_connmark.c | 5 +++--
>> net/sched/act_csum.c | 8 ++++----
>> net/sched/act_gact.c | 5 +++--
>> net/sched/act_ife.c | 12 +++++-------
>> net/sched/act_ipt.c | 5 +++--
>> net/sched/act_mirred.c | 5 ++---
>> net/sched/act_nat.c | 5 +++--
>> net/sched/act_pedit.c | 5 +++--
>> net/sched/act_police.c | 8 +++-----
>> net/sched/act_sample.c | 8 +++-----
>> net/sched/act_simple.c | 5 +++--
>> net/sched/act_skbedit.c | 5 +++--
>> net/sched/act_skbmod.c | 8 +++-----
>> net/sched/act_tunnel_key.c | 8 +++-----
>> net/sched/act_vlan.c | 8 +++-----
>> 16 files changed, 51 insertions(+), 57 deletions(-)
>>
>>diff --git a/net/sched/act_bpf.c b/net/sched/act_bpf.c
>>index 5d95c43..5554bf7 100644
>>--- a/net/sched/act_bpf.c
>>+++ b/net/sched/act_bpf.c
>>@@ -311,9 +311,10 @@ static int tcf_bpf_init(struct net *net, struct nlattr *nla,
>> if (bind)
>> return 0;
>>
>>- tcf_idr_release(*act, bind);
>>- if (!replace)
>>+ if (!replace) {
>>+ tcf_idr_release(*act, bind);
>> return -EEXIST;
>>+ }
>> }
>>
>> is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS];
>
> …