linux-kernel - Re: [PATCH net v2] net/smc: fix neighbour and rtable leak in smc_ib_find

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Date: Tue, 7 May 2024 15:12:39 +0200
From: Wenjia Zhang <wenjia@...ux.ibm.com>
To: Wen Gu <guwen@...ux.alibaba.com>, jaka@...ux.ibm.com, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com
Cc: kgraul@...ux.ibm.com, alibuda@...ux.alibaba.com, tonylu@...ux.alibaba.com,
        linux-s390@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net v2] net/smc: fix neighbour and rtable leak in
 smc_ib_find_route()



On 07.05.24 14:53, Wen Gu wrote:
> In smc_ib_find_route(), the neighbour found by neigh_lookup() and rtable
> resolved by ip_route_output_flow() are not released or put before return.
> It may cause the refcount leak, so fix it.
> 
> Link: https://lore.kernel.org/r/20240506015439.108739-1-guwen@linux.alibaba.com
> Fixes: e5c4744cfb59 ("net/smc: add SMC-Rv2 connection establishment")
> Signed-off-by: Wen Gu <guwen@...ux.alibaba.com>
> ---
> v2->v1
> - call ip_rt_put() to release rt as well.
> ---
>   net/smc/smc_ib.c | 19 ++++++++++++-------
>   1 file changed, 12 insertions(+), 7 deletions(-)
> 
> diff --git a/net/smc/smc_ib.c b/net/smc/smc_ib.c
> index 97704a9e84c7..9297dc20bfe2 100644
> --- a/net/smc/smc_ib.c
> +++ b/net/smc/smc_ib.c
> @@ -209,13 +209,18 @@ int smc_ib_find_route(struct net *net, __be32 saddr, __be32 daddr,
>   	if (IS_ERR(rt))
>   		goto out;
>   	if (rt->rt_uses_gateway && rt->rt_gw_family != AF_INET)
> -		goto out;
> -	neigh = rt->dst.ops->neigh_lookup(&rt->dst, NULL, &fl4.daddr);
> -	if (neigh) {
> -		memcpy(nexthop_mac, neigh->ha, ETH_ALEN);
> -		*uses_gateway = rt->rt_uses_gateway;
> -		return 0;
> -	}
> +		goto out_rt;
> +	neigh = dst_neigh_lookup(&rt->dst, &fl4.daddr);
> +	if (!neigh)
> +		goto out_rt;
> +	memcpy(nexthop_mac, neigh->ha, ETH_ALEN);
> +	*uses_gateway = rt->rt_uses_gateway;
> +	neigh_release(neigh);
> +	ip_rt_put(rt);
> +	return 0;
> +
> +out_rt:
> +	ip_rt_put(rt);
>   out:
>   	return -ENOENT;
>   }

Thank you for fixing it!

Reviewed-and-tested-by: Wenjia Zhang <wenjia@...ux.ibm.com>