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 15:17:59 -0700 [thread overview]
Message-ID: <20260519151759.690eda98@kernel.org> (raw)
In-Reply-To: <CANn89i+pLyyDedP7YeFLxYrESrhLvFrRoeaVJHrG=aDEnM0csA@mail.gmail.com>
On Tue, 19 May 2026 09:53:08 -0700 Eric Dumazet wrote:
> On Tue, May 19, 2026 at 9:39 AM Jakub Kicinski <kuba@kernel.org> wrote:
> >
> > 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?
>
> We cannot prevent this unless we add a mutual exclusion.
Today its under rtnl_lock, AFAICT, so nop, if we want to lift
rtnl_lock from RTM_NEWLINKPROP we can probably slide the props
under dev->lock or add a new lock?
next prev parent reply other threads:[~2026-05-19 22:18 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
2026-05-19 16:53 ` Eric Dumazet
2026-05-19 22:17 ` Jakub Kicinski [this message]
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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