netdev - Re: [PATCH net-next] netlink: correct nlmsg size for multicast notifications

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Message-ID: <CANn89iKcVDM-na-kF+o3octj16K-8ZRLFZvShTR_rLAKb-CSoA@mail.gmail.com>
Date: Thu, 19 Dec 2024 14:42:02 +0100
From: Eric Dumazet <edumazet@...gle.com>
To: Yuyang Huang <yuyanghuang@...gle.com>
Cc: "David S. Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>, David Ahern <dsahern@...nel.org>, 
	roopa@...ulusnetworks.com, jiri@...nulli.us, stephen@...workplumber.org, 
	jimictw@...gle.com, prohr@...gle.com, liuhangbin@...il.com, 
	nicolas.dichtel@...nd.com, andrew@...n.ch, pruddy@...tta.att-mail.com, 
	netdev@...r.kernel.org, Maciej Żenczykowski <maze@...gle.com>, 
	Lorenzo Colitti <lorenzo@...gle.com>
Subject: Re: [PATCH net-next] netlink: correct nlmsg size for multicast notifications

On Thu, Dec 19, 2024 at 2:27 PM Yuyang Huang <yuyanghuang@...gle.com> wrote:
>
> Corrected the netlink message size calculation for multicast group
> join/leave notifications. The previous calculation did not account for
> the inclusion of both IPv4/IPv6 addresses and ifa_cacheinfo in the
> payload. This fix ensures that the allocated message size is
> sufficient to hold all necessary information.
>
> Fixes: 2c2b61d2138f ("netlink: add IGMP/MLD join/leave notifications")
> Cc: Maciej Żenczykowski <maze@...gle.com>
> Cc: Lorenzo Colitti <lorenzo@...gle.com>
> Signed-off-by: Yuyang Huang <yuyanghuang@...gle.com>
> ---
>  net/ipv4/igmp.c  | 4 +++-
>  net/ipv6/mcast.c | 4 +++-
>  2 files changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
> index 8a370ef37d3f..4e2f1497f320 100644
> --- a/net/ipv4/igmp.c
> +++ b/net/ipv4/igmp.c
> @@ -1473,7 +1473,9 @@ static void inet_ifmcaddr_notify(struct net_device *dev,
>         int err = -ENOMEM;
>
>         skb = nlmsg_new(NLMSG_ALIGN(sizeof(struct ifaddrmsg)) +
> -                       nla_total_size(sizeof(__be32)), GFP_ATOMIC);
> +                       nla_total_size(sizeof(__be32)) +
> +                       nla_total_size(sizeof(struct ifa_cacheinfo)),
> +                       GFP_ATOMIC);
>         if (!skb)
>                 goto error;
>
> diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
> index 587831c148de..b7430f15d1fc 100644
> --- a/net/ipv6/mcast.c
> +++ b/net/ipv6/mcast.c
> @@ -920,7 +920,9 @@ static void inet6_ifmcaddr_notify(struct net_device *dev,
>         int err = -ENOMEM;
>
>         skb = nlmsg_new(NLMSG_ALIGN(sizeof(struct ifaddrmsg)) +
> -                       nla_total_size(16), GFP_ATOMIC);
> +                       nla_total_size(16) +

While we are at it , can you use nla_total_size(sizeof(struct in6_addr))

inet6_fill_ifmcaddr() got  an EXPORT_SYMBOL() for no good reason,
please remove it.
Squash the following in v2, thanks !

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 2e2684886953d55140cd3d4a1e024b5218331a49..4da409bc45777f60fd37bdee541c61165a51d22c
100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -5239,7 +5239,6 @@ int inet6_fill_ifmcaddr(struct sk_buff *skb,
        nlmsg_end(skb, nlh);
        return 0;
 }
-EXPORT_SYMBOL(inet6_fill_ifmcaddr);

 static int inet6_fill_ifacaddr(struct sk_buff *skb,
                               const struct ifacaddr6 *ifaca,