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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Kuniyuki Iwashima , Mahesh Bandewar , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, 1342116488@qq.com Subject: Re: [PATCH net] ipvlan: update port flags only after ipvlan_set_port_mode() succeeds Message-ID: References: <20261111064655.233265-1-sunwenbo@cmss.chinamobile.com> X-Mailing-List: netdev@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261111064655.233265-1-sunwenbo@cmss.chinamobile.com> Hi Wenbo, On Wed, Nov 11, 2026 at 02:46:55PM +0800, Wenbo Sun wrote: > In ipvlan_link_new(), the shared port->flags is updated before > calling ipvlan_set_port_mode(). If ipvlan_set_port_mode() fails (e.g. > switching to L3S mode without CONFIG_IPVLAN_L3S), the error unwinds via > unlink_netdev, but the shared port->flags has already been modified and > is never restored. If ipvlan_set_port_mode() failed, the unregister_netdevice(dev) will be called. Does port->flags still need to restore? Thanks Hangbin > > As a result, subsequent operations on existing ipvlan interfaces on the > same lower device operate with corrupted port flags (e.g., VEPA or > PRIVATE flags inadvertently set or cleared). > > Fix this by deferring the update of port->flags until after > ipvlan_set_port_mode() returns successfully, matching the behaviour of > ipvlan_nl_changelink(). > > This issue was identified with the assistance of an LLM-based code > review tool, confirmed by reproducing the state corruption in a > User-Mode Linux (UML) environment when ipvlan_set_port_mode() fails, > and verified in UML that the shared port flags remain unchanged upon > failure. > > Fixes: a190d04db937 ("ipvlan: introduce 'private' attribute for all existing modes.") > Signed-off-by: Wenbo Sun > --- > drivers/net/ipvlan/ipvlan_main.c | 12 ++++++------ > 1 file changed, 6 insertions(+), 6 deletions(-) > > diff --git a/drivers/net/ipvlan/ipvlan_main.c b/drivers/net/ipvlan/ipvlan_main.c > index f29864db662a..5732b167c5b3 100644 > --- a/drivers/net/ipvlan/ipvlan_main.c > +++ b/drivers/net/ipvlan/ipvlan_main.c > @@ -678,12 +678,6 @@ int ipvlan_link_new(struct net_device *dev, struct rtnl_newlink_params *params, > if (err) > goto remove_ida; > > - /* Flags are per port and latest update overrides. User has > - * to be consistent in setting it just like the mode attribute. > - */ > - if (data && data[IFLA_IPVLAN_FLAGS]) > - port->flags = nla_get_u16(data[IFLA_IPVLAN_FLAGS]); > - > if (data && data[IFLA_IPVLAN_MODE]) > mode = nla_get_u16(data[IFLA_IPVLAN_MODE]); > > @@ -691,6 +685,12 @@ int ipvlan_link_new(struct net_device *dev, struct rtnl_newlink_params *params, > if (err) > goto unlink_netdev; > > + /* Flags are per port and latest update overrides. User has > + * to be consistent in setting it just like the mode attribute. > + */ > + if (data && data[IFLA_IPVLAN_FLAGS]) > + port->flags = nla_get_u16(data[IFLA_IPVLAN_FLAGS]); > + > mutex_lock(&port->pnodes_lock); > list_add_tail_rcu(&ipvlan->pnode, &port->ipvlans); > mutex_unlock(&port->pnodes_lock); > -- > 2.33.0 > > >