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

>
>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];

[...]

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