netdev - Re: [PATCH net v2 3/3] net/sched: flower: fix error handler on replace

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Date: Thu, 4 May 2023 15:21:24 -0300
From: Pedro Tammela <pctammela@...atatu.com>
To: Vlad Buslov <vladbu@...dia.com>, pabeni@...hat.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, ivecera@...hat.com
Subject: Re: [PATCH net v2 3/3] net/sched: flower: fix error handler on
 replace

On 04/05/2023 15:16, 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>

Reviewed-by: Pedro Tammela <pctammela@...atatu.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 ac4f344c52e0..9dbc43388e57 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);