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Date: Fri, 27 Feb 2026 10:17:29 +0000
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From: "Jiayuan Chen" <jiayuan.chen@linux.dev>
Message-ID: <4cc373b555ec3d6ff57037c569d12966a8b701db@linux.dev>
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Subject: Re: [PATCH net v2 1/2] bonding: fix null-ptr-deref in
 bond_rr_gen_slave_id()
To: "Sebastian Andrzej Siewior" <bigeasy@linutronix.de>
Cc: netdev@vger.kernel.org, jiayuna.chen@linux.dev, jiayuna.chen@shopee.com,
 "Jiayuan Chen" <jiayuan.chen@shopee.com>,
 syzbot+80e046b8da2820b6ba73@syzkaller.appspotmail.com, "Jay Vosburgh"
 <jv@jvosburgh.net>, "Andrew Lunn" <andrew+netdev@lunn.ch>, "David S.
 Miller" <davem@davemloft.net>, "Eric Dumazet" <edumazet@google.com>,
 "Jakub Kicinski" <kuba@kernel.org>, "Paolo Abeni" <pabeni@redhat.com>,
 "Simon Horman" <horms@kernel.org>, "Alexei Starovoitov" <ast@kernel.org>,
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In-Reply-To: <20260227094558._Fna2iSe@linutronix.de>
References: <20260227092254.272603-1-jiayuan.chen@linux.dev>
 <20260227092254.272603-2-jiayuan.chen@linux.dev>
 <20260227094558._Fna2iSe@linutronix.de>
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2026/2/27 17:45, "Sebastian Andrzej Siewior" <bigeasy@linutronix.de mailt=
o:bigeasy@linutronix.de?to=3D%22Sebastian%20Andrzej%20Siewior%22%20%3Cbig=
easy%40linutronix.de%3E > wrote:


>=20
>=20On 2026-02-27 17:22:49 [+0800], Jiayuan Chen wrote:
>=20
>=20>=20
>=20> --- a/drivers/net/bonding/bond_main.c
> >  +++ b/drivers/net/bonding/bond_main.c
> >  @@ -6458,6 +6458,12 @@ int bond_create(struct net *net, const char *=
name)
> >  dev_net_set(bond_dev, net);
> >  bond_dev->rtnl_link_ops =3D &bond_link_ops;
> >=20=20
>=20>  + res =3D bond_create_init(bond);
> >=20
>=20Wouldn't it be better to put into bond_init()?
>=20
>=20I haven't look into it but when can the bond_mode be changed?
>=20
>=20Sebastian
>

Thanks! bond_init() (ndo_init) is indeed a better fit, it is called by re=
gister_netdevice()
and naturally covers both bond_create() and bond_newlink() without a sepa=
rate helper.

bond_mode can be changed after device creation via sysfs or netlink, a bo=
nd created
in active-backup mode can later be switched to round-robin, which means t=
he allocation
must not be conditional on the mode at creation time.