netdev - Re: [PATH wpan v2] ieee802154: hwsim: Fix possible memory leaks

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Date:   Sat, 8 Apr 2023 11:04:58 -0400
From:   Alexander Aring <aahringo@...hat.com>
To:     Chen Aotian <chenaotian2@....com>
Cc:     alex.aring@...il.com, stefan@...enfreihafen.org,
        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
Subject: Re: [PATH wpan v2] ieee802154: hwsim: Fix possible memory leaks

Hi,

On Sat, Apr 8, 2023 at 4:22 AM Chen Aotian <chenaotian2@....com> 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>
> Signed-off-by: Chen Aotian <chenaotian2@....com>
> ---
>
> 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..6ffcadb9d 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,
> +                                                       lock_is_held(&hwsim_phys_lock));

I think lockdep_is_held() should be correct here.

- Alex