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Subject[PATCH 4.9 066/104] bridge: netlink: register netdevice before executing changelink
Date
4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ido Schimmel <idosch@mellanox.com>


[ Upstream commit 5b8d5429daa05bebef6ffd3297df3b502cc6f184 ]

Peter reported a kernel oops when executing the following command:

$ ip link add name test type bridge vlan_default_pvid 1

[13634.939408] BUG: unable to handle kernel NULL pointer dereference at
0000000000000190
[13634.939436] IP: __vlan_add+0x73/0x5f0
[...]
[13634.939783] Call Trace:
[13634.939791] ? pcpu_next_unpop+0x3b/0x50
[13634.939801] ? pcpu_alloc+0x3d2/0x680
[13634.939810] ? br_vlan_add+0x135/0x1b0
[13634.939820] ? __br_vlan_set_default_pvid.part.28+0x204/0x2b0
[13634.939834] ? br_changelink+0x120/0x4e0
[13634.939844] ? br_dev_newlink+0x50/0x70
[13634.939854] ? rtnl_newlink+0x5f5/0x8a0
[13634.939864] ? rtnl_newlink+0x176/0x8a0
[13634.939874] ? mem_cgroup_commit_charge+0x7c/0x4e0
[13634.939886] ? rtnetlink_rcv_msg+0xe1/0x220
[13634.939896] ? lookup_fast+0x52/0x370
[13634.939905] ? rtnl_newlink+0x8a0/0x8a0
[13634.939915] ? netlink_rcv_skb+0xa1/0xc0
[13634.939925] ? rtnetlink_rcv+0x24/0x30
[13634.939934] ? netlink_unicast+0x177/0x220
[13634.939944] ? netlink_sendmsg+0x2fe/0x3b0
[13634.939954] ? _copy_from_user+0x39/0x40
[13634.939964] ? sock_sendmsg+0x30/0x40
[13634.940159] ? ___sys_sendmsg+0x29d/0x2b0
[13634.940326] ? __alloc_pages_nodemask+0xdf/0x230
[13634.940478] ? mem_cgroup_commit_charge+0x7c/0x4e0
[13634.940592] ? mem_cgroup_try_charge+0x76/0x1a0
[13634.940701] ? __handle_mm_fault+0xdb9/0x10b0
[13634.940809] ? __sys_sendmsg+0x51/0x90
[13634.940917] ? entry_SYSCALL_64_fastpath+0x1e/0xad

The problem is that the bridge's VLAN group is created after setting the
default PVID, when registering the netdevice and executing its
ndo_init().

Fix this by changing the order of both operations, so that
br_changelink() is only processed after the netdevice is registered,
when the VLAN group is already initialized.

Fixes: b6677449dff6 ("bridge: netlink: call br_changelink() during br_dev_newlink()")
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reported-by: Peter V. Saveliev <peter@svinota.eu>
Tested-by: Peter V. Saveliev <peter@svinota.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/bridge/br_netlink.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -1098,11 +1098,14 @@ static int br_dev_newlink(struct net *sr
spin_unlock_bh(&br->lock);
}

- err = br_changelink(dev, tb, data);
+ err = register_netdevice(dev);
if (err)
return err;

- return register_netdevice(dev);
+ err = br_changelink(dev, tb, data);
+ if (err)
+ unregister_netdevice(dev);
+ return err;
}

static size_t br_get_size(const struct net_device *brdev)

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