From: Jakub Kicinski <kuba@kernel.org>
To: Eric Dumazet <edumazet@google.com>
Cc: "David S . Miller" <davem@davemloft.net>,
Paolo Abeni <pabeni@redhat.com>, Simon Horman <horms@kernel.org>,
Kuniyuki Iwashima <kuniyu@google.com>,
netdev@vger.kernel.org, eric.dumazet@gmail.com
Subject: Re: [PATCH v2 net-next 1/2] rtnetlink: use nla_nest_end_safe() in rtnl_fill_prop_list()
Date: Tue, 19 May 2026 09:39:04 -0700 [thread overview]
Message-ID: <20260519093904.49298543@kernel.org> (raw)
In-Reply-To: <20260519114355.2769474-2-edumazet@google.com>
On Tue, 19 May 2026 11:43:54 +0000 Eric Dumazet wrote:
> Avoid corrupting a netlink message and confuse user space in the
> unlikely case rtnl_fill_prop_list was able to produce a very big
> nested element.
Should we not prevent it from happening in the first place?
IIUC otherwise if user adds a lot of altnames ip link will no longer
work?
> diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
> index 6a5e9ace55a0880d7b1e4303d12dc0a8b8b7c5ed..ae0254f19178735b2805a8189e81a960a49b2858 100644
> --- a/net/core/rtnetlink.c
> +++ b/net/core/rtnetlink.c
> @@ -1971,7 +1971,9 @@ static int rtnl_fill_prop_list(struct sk_buff *skb,
> if (ret <= 0)
> goto nest_cancel;
>
> - nla_nest_end(skb, prop_list);
> + if (nla_nest_end_safe(skb, prop_list) < 0)
> + goto nest_cancel;
> +
> return 0;
>
> nest_cancel:
next prev parent reply other threads:[~2026-05-19 16:39 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-19 11:43 [PATCH v2 net-next 0/2] rtnetlink: RTNL avoidance in rtnl_getlink() Eric Dumazet
2026-05-19 11:43 ` [PATCH v2 net-next 1/2] rtnetlink: use nla_nest_end_safe() in rtnl_fill_prop_list() Eric Dumazet
2026-05-19 16:39 ` Jakub Kicinski [this message]
2026-05-19 16:53 ` Eric Dumazet
2026-05-19 22:17 ` Jakub Kicinski
2026-05-19 11:43 ` [PATCH v2 net-next 2/2] rtnetlink: do not acquire RTNL for RTM_GETLINK with RTEXT_FILTER_NAME_ONLY Eric Dumazet
2026-05-19 16:37 ` [PATCH v2 net-next 0/2] rtnetlink: RTNL avoidance in rtnl_getlink() Jakub Kicinski
2026-05-19 17:17 ` Eric Dumazet
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