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Subject: Re: [PATCH] openvswitch: Fix a possible memory leak on dst_cache
To:     Haishuang Yan <yanhaishuang@cmss.chinamobile.com>,
        Pravin B Shelar <pshelar@ovn.org>,
        "David S. Miller" <davem@davemloft.net>
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org
References: <1563466028-2531-1-git-send-email-yanhaishuang@cmss.chinamobile.com>
From:   Gregory Rose <gvrose8192@gmail.com>
Message-ID: <9b231232-dd6e-5733-2af9-e2fb3d6ae0a4@gmail.com>
Date:   Thu, 18 Jul 2019 15:12:43 -0700
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On 7/18/2019 9:07 AM, Haishuang Yan wrote:
> dst_cache should be destroyed when fail to add flow actions.
>
> Fixes: d71785ffc7e7 ("net: add dst_cache to ovs vxlan lwtunnel")
> Signed-off-by: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
> ---
>   net/openvswitch/flow_netlink.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/net/openvswitch/flow_netlink.c b/net/openvswitch/flow_netlink.c
> index d7559c6..1fd1cdd 100644
> --- a/net/openvswitch/flow_netlink.c
> +++ b/net/openvswitch/flow_netlink.c
> @@ -2608,6 +2608,7 @@ static int validate_and_copy_set_tun(const struct nlattr *attr,
>   			 sizeof(*ovs_tun), log);
>   	if (IS_ERR(a)) {
>   		dst_release((struct dst_entry *)tun_dst);
> +		dst_cache_destroy(&tun_dst->u.tun_info.dst_cache);
>   		return PTR_ERR(a);
>   	}
>   

Nack.

dst_release will decrement the ref count and will 
call_rcu(&dst->rcu_head, dst_destroy_rcu) if the ref count is zero.  No 
other net drivers call dst_destroy SFAICT.

Haishuang,

are you trying to fix some specific problem here?

Thanks,

- Greg