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We encountered a crash: in the packet receiving process, we got an
illegal VLAN device address, but the VLAN device address saved in vmcore
is correct. After checking the code, we found a possible data
competition:
CPU 0: CPU 1:
(RCU read lock) (RTNL lock)
vlan_do_receive() register_vlan_dev()
vlan_find_dev()
->__vlan_group_get_device() ->vlan_group_prealloc_vid()
In vlan_group_prealloc_vid(), We need to make sure that memset()
in kzalloc() is executed before assigning value to vlan devices array:
=================================
kzalloc()
->memset(object, 0, size)
smp_wmb()
vg->vlan_devices_arrays[pidx][vidx] = array;
==================================
Because __vlan_group_get_device() function depends on this order.
otherwise we may get a wrong address from the hardware cache on
another cpu.
So fix it by adding memory barrier instruction to ensure the order
of memory operations.
Signed-off-by: Di Zhu <zhudi21@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
c1102e9d49