netdev - Re: [PATH wpan v3] ieee802154: hwsim: Fix possible memory leaks

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Date:   Wed, 12 Apr 2023 21:48:25 +0200
From:   Stefan Schmidt <stefan@...enfreihafen.org>
To:     Chen Aotian <chenaotian2@....com>, alex.aring@...il.com
Cc:     miquel.raynal@...tlin.com, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        linux-wpan@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Alexander Aring <aahringo@...hat.com>
Subject: Re: [PATH wpan v3] ieee802154: hwsim: Fix possible memory leaks

Hello.

On 09.04.23 04:20, Chen Aotian wrote:
> After replacing e->info, it is necessary to free the old einfo.
> 
> Fixes: f25da51fdc38 ("ieee802154: hwsim: add replacement for fakelb")
> Reviewed-by: Miquel Raynal <miquel.raynal@...tlin.com>
> Reviewed-by: Alexander Aring <aahringo@...hat.com>
> Signed-off-by: Chen Aotian <chenaotian2@....com>
> ---
> 
> V2 -> V3:
> * lock_is_held() => lockdep_is_held().(thanks for Alexander)
> 
> V1 -> V2:
> * Using rcu_replace_pointer() is better then rcu_dereference()
>    and rcu_assign_pointer().
> 
>   drivers/net/ieee802154/mac802154_hwsim.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ieee802154/mac802154_hwsim.c b/drivers/net/ieee802154/mac802154_hwsim.c
> index 8445c2189..31cba9aa7 100644
> --- a/drivers/net/ieee802154/mac802154_hwsim.c
> +++ b/drivers/net/ieee802154/mac802154_hwsim.c
> @@ -685,7 +685,7 @@ static int hwsim_del_edge_nl(struct sk_buff *msg, struct genl_info *info)
>   static int hwsim_set_edge_lqi(struct sk_buff *msg, struct genl_info *info)
>   {
>   	struct nlattr *edge_attrs[MAC802154_HWSIM_EDGE_ATTR_MAX + 1];
> -	struct hwsim_edge_info *einfo;
> +	struct hwsim_edge_info *einfo, *einfo_old;
>   	struct hwsim_phy *phy_v0;
>   	struct hwsim_edge *e;
>   	u32 v0, v1;
> @@ -723,8 +723,10 @@ static int hwsim_set_edge_lqi(struct sk_buff *msg, struct genl_info *info)
>   	list_for_each_entry_rcu(e, &phy_v0->edges, list) {
>   		if (e->endpoint->idx == v1) {
>   			einfo->lqi = lqi;
> -			rcu_assign_pointer(e->info, einfo);
> +			einfo_old = rcu_replace_pointer(e->info, einfo,
> +							lockdep_is_held(&hwsim_phys_lock));
>   			rcu_read_unlock();
> +			kfree_rcu(einfo_old, rcu);
>   			mutex_unlock(&hwsim_phys_lock);
>   			return 0;
>   		}

This patch has been applied to the wpan tree and will be
part of the next pull request to net. Thanks!

regards
Stefan Schmidt