netdev - Re: [PATCH net 2/2] net/sched: flower: fix error handler on replace

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Message-ID: <4a647080-cdf6-17e3-6e21-50250722e698@mojatatu.com>
Date:   Wed, 26 Apr 2023 11:22:39 -0300
From:   Pedro Tammela <pctammela@...atatu.com>
To:     Vlad Buslov <vladbu@...dia.com>, davem@...emloft.net,
        kuba@...nel.org
Cc:     netdev@...r.kernel.org, jhs@...atatu.com, xiyou.wangcong@...il.com,
        jiri@...nulli.us, marcelo.leitner@...il.com, paulb@...dia.com,
        simon.horman@...igine.com
Subject: Re: [PATCH net 2/2] net/sched: flower: fix error handler on replace

On 26/04/2023 09:14, Vlad Buslov wrote:
> When replacing a filter (i.e. 'fold' pointer is not NULL) the insertion of
> new filter to idr is postponed until later in code since handle is already
> provided by the user. However, the error handling code in fl_change()
> always assumes that the new filter had been inserted into idr. If error
> handler is reached when replacing existing filter it may remove it from idr
> therefore making it unreachable for delete or dump afterwards. Fix the
> issue by verifying that 'fold' argument wasn't provided by caller before
> calling idr_remove().
> 
> Fixes: 08a0063df3ae ("net/sched: flower: Move filter handle initialization earlier")
> Signed-off-by: Vlad Buslov <vladbu@...dia.com>
> ---
>   net/sched/cls_flower.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
> index 1844545bef37..a1c4ee2e0be2 100644
> --- a/net/sched/cls_flower.c
> +++ b/net/sched/cls_flower.c
> @@ -2339,7 +2339,8 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
>   errout_mask:
>   	fl_mask_put(head, fnew->mask);
>   errout_idr:
> -	idr_remove(&head->handle_idr, fnew->handle);
> +	if (!fold)
> +		idr_remove(&head->handle_idr, fnew->handle);
>   	__fl_put(fnew);
>   errout_tb:
>   	kfree(tb);

Actually this seems to be fixing the same issue:
https://lore.kernel.org/all/20230425140604.169881-1-ivecera@redhat.com/