Re: [BUG] [FIX] net: dsa: oops in br_vlan_enabled

[Florian Fainelli <f.fainelli@gmail.com>]

On February 18, 2019 9:11:27 AM PST, Frank Wunderlich <frank-w@public-files.de> wrote:
>Hi,
>
>tried your Patch but crashes the same way:

Yes the lower_dev targeted by switched does point to the DSA slave network device, but we really don't have dp->bridge_dev assigned since the physical DSA port was not enslaved in the bridge. Will follow up with a correct version late today.

>
>[  107.416972] [<bf0fde88>] (br_vlan_enabled [bridge]) from
>[<bf14e234>] (dsa_po
>rt_vlan_add+0x60/0xbc [dsa_core])                                      
>        
>[  107.426939] [<bf14e234>] (dsa_port_vlan_add [dsa_core]) from
>[<bf14eba4>] (ds
>a_slave_port_obj_add+0x64/0x68 [dsa_core])                             
>        
>[  107.437666] [<bf14eba4>] (dsa_slave_port_obj_add [dsa_core]) from
>[<c0b4e684>
>] (__switchdev_port_obj_add+0x50/0xc4)                                 
>        
>[  107.448029] [<c0b4e684>] (__switchdev_port_obj_add) from
>[<c0b4e6d4>] (__swit
>chdev_port_obj_add+0xa0/0xc4)                                          
>        
>[  107.457612] [<c0b4e6d4>] (__switchdev_port_obj_add) from
>[<c0b4e758>] (switch
>dev_port_obj_add_now+0x60/0x130)                                       
>        
>[  107.467453] [<c0b4e758>] (switchdev_port_obj_add_now) from
>[<c0b4eb94>] (swit
>chdev_port_obj_add+0x44/0x190)                                         
>        
>[  107.477181] [<c0b4eb94>] (switchdev_port_obj_add) from [<bf1013d0>]
>(br_switc
>hdev_port_vlan_add+0x60/0x7c [bridge])                                 
>        
>[  107.487644] [<bf1013d0>] (br_switchdev_port_vlan_add [bridge]) from
>[<bf0ff25
>0>] (__vlan_add+0xb0/0x620 [bridge])
>
>regards Frank
>
>
>> Gesendet: Montag, 18. Februar 2019 um 00:20 Uhr
>> Von: "Florian Fainelli" <f.fainelli@gmail.com>
>> An: "Frank Wunderlich" <frank-w@public-files.de>,
>netdev@vger.kernel.org, "Andrew Lunn" <andrew@lunn.ch>, "Vivien
>Didelot" <vivien.didelot@gmail.com>
>> Betreff: Re: [BUG] [FIX] net: dsa: oops in br_vlan_enabled
>>
>> 
>> 
>> On 2/17/2019 9:13 AM, Florian Fainelli wrote:
>> > Hi Frank,
>> > 
>> > On 2/16/2019 8:22 AM, Frank Wunderlich wrote:
>> >> Hi,
>> >>
>> >> i've found an oops in 4.19.23/10, seems to be fixed anyhow in 5.0
>(also works in 4.14.101)
>> >>
>> >> root@bpi-r2:~# ip link add link lan0 name lan0.5 type vlan id 5
>> >> root@bpi-r2:~# ip addr add 192.168.5.200/24 brd 192.168.5.255 dev
>lan0.5
>> >> root@bpi-r2:~# ip link set dev lan0 up
>> >> root@bpi-r2:~# ip link set dev lan0.5 up
>> > 
>> > So that these steps don't involve a bridge, and because we don't
>(yet)
>> > implment ndo_vlan_rx_{add,kill}_vid() netdevice_ops, there is no
>VLAN
>> > programming, it's all software
>> > 
>> >>
>> >> 12: lan0.5@lan0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500
>qdisc noqueue state LOWERLAYERDOWN group default qlen 1000
>> >>     link/ether 02:02:02:02:02:02 brd ff:ff:ff:ff:ff:ff
>> >>     inet 192.168.5.200/24 brd 192.168.5.255 scope global lan0.5
>> >>        valid_lft forever preferred_lft forever
>> >>
>> >> root@bpi-r2:~# brctl addbr bridge_name
>> >> root@bpi-r2:~# brctl addif bridge_name lan0.5
>> > 
>> > Unless you changed the bridge to have VLAN filtering/awareness
>with:
>> > 
>> > echo 1 > /sys/class/net/bridge_name/bridge/vlan_filtering
>> > 
>> > There will be no VLAN configuration/objects pushed to DSA since
>commit
>> > 2ea7a679ca2abd251c1ec03f20508619707e1749 ("net: dsa: Don't add
>vlans
>> > when vlan filtering is disabled") so I am not sure how you got into
>that
>> > situation because prior to pushing a VLAN object, the port must be
>part
>> > of a bridge, so the steps typically look like:
>> > 
>> > - port_bridge_join which assigns dp->bridge_dev
>> > - port_vlan_add
>> > 
>> > Does your 4.19.23 kernel somehow change how VLAN objects are pushed
>down
>> > the switch driver?
>> > 
>> >> [  352.057128] bridge_name: port 1(lan0.5) entered blocking state
>> >> [  352.063065] bridge_name: port 1(lan0.5) entered disabled state
>> >> [  352.069181] device lan0.5 entered promiscuous mode
>> >> [  352.074018] device lan0 entered promiscuous mode
>> >> [  352.078906] Unable to handle kernel NULL pointer dereference at
>virtual address 00000558
>> >> ...
>> >> [  352.493085] [<bf0fde88>] (br_vlan_enabled [bridge]) from
>[<bf12c234>] (dsa_port_vlan_add+0x60/0xbc [dsa_core])
>> >> [  352.503050] [<bf12c234>] (dsa_port_vlan_add [dsa_core]) from
>[<bf12cb64>] (dsa_slave_port_obj_add+0x4c/0x50 [dsa_core])
>> >> [  352.513776] [<bf12cb64>] (dsa_slave_port_obj_add [dsa_core])
>from [<c0b4e2d4>] (__switchdev_port_obj_add+0x50/0xc4)
>> >> [  352.524138] [<c0b4e2d4>] (__switchdev_port_obj_add) from
>[<c0b4e324>] (__switchdev_port_obj_add+0xa0/0xc4)
>> >> [  352.533721] [<c0b4e324>] (__switchdev_port_obj_add) from
>[<c0b4e3a8>] (switchdev_port_obj_add_now+0x60/0x130)
>> >> [  352.543562] [<c0b4e3a8>] (switchdev_port_obj_add_now) from
>[<c0b4e7e4>] (switchdev_port_obj_add+0x44/0x190)
>> >> [  352.553284] [<c0b4e7e4>] (switchdev_port_obj_add) from
>[<bf1013d0>] (br_switchdev_port_vlan_add+0x60/0x7c [bridge])
>> >> [  352.563733] [<bf1013d0>] (br_switchdev_port_vlan_add [bridge])
>from [<bf0ff250>] (__vlan_add+0xb0/0x620 [bridge])
>> >> [  352.574007] [<bf0ff250>] (__vlan_add [bridge]) from
>[<bf0ffd04>] (nbp_vlan_add+0xc4/0x150 [bridge])
>> >> [  352.583073] [<bf0ffd04>] (nbp_vlan_add [bridge]) from
>[<bf0ffec4>] (nbp_vlan_init+0x134/0x164 [bridge])
>> >> [  352.592482] [<bf0ffec4>] (nbp_vlan_init [bridge]) from
>[<bf0edd4c>] (br_add_if+0x40c/0x5fc [bridge])
>> >> [  352.601632] [<bf0edd4c>] (br_add_if [bridge]) from [<bf0eeb14>]
>(add_del_if+0x6c/0x80 [bridge])
>> >> [  352.610351] [<bf0eeb14>] (add_del_if [bridge]) from
>[<bf0ef5b0>] (br_dev_ioctl+0x7c/0x9c [bridge])
>> >> [  352.619290] [<bf0ef5b0>] (br_dev_ioctl [bridge]) from
>[<c09583d4>] (dev_ifsioc+0x184/0x324)
>> >> [  352.627582] [<c09583d4>] (dev_ifsioc) from [<c09589e8>]
>(dev_ioctl+0x32c/0x5cc)
>> >> [  352.634837] [<c09589e8>] (dev_ioctl) from [<c090913c>]
>(sock_ioctl+0x3bc/0x580)
>> >>
>> >>
>> >> since my 4.19.23 kernel is modified a bit i tried with 4.19.10
>without my net modifications and it is still reproducable with steps
>above (create a vlan on dsa-user-port and then use it in a bridge)
>> >>
>> >> i fixed it with these changes:
>> 
>> Your fix is undoing the commit from Andrew I just referenced, so it
>is
>> definitively not the right fix because it will push VLAN objects down
>to
>> a non-VLAN aware bridge, not that this is really a problem, but it
>> should not be happening anyway.
>> 
>> The problem appears to be the following though: you are enslaving a
>VLAN
>> device, which does not have switchdev_ops, so we recurse into the
>lower
>> device, which is the DSA network device, which does have
>switchdev_ops
>> defined. Once we are there we check the orig_dev against being a
>bridge
>> master network device, but we are not checking that it's a VLAN
>device
>> so we end-up assuming it is a DSA network device, we de-reference
>> garbage by checking br_vlan_enabled(dp->bridge_dev) because there is
>> simply no such data structure associated with the VLAN device.
>> 
>> The attached patch should help.
>> 
>> This is no longer a problem in newer kernels because the switchdev
>> operations use a notifier which checks the target network device to
>be DSA.
>> -- 
>> Florian
>> 

-- 
Florian