ice: add NULL check in eswitch lag check

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: ice: add NULL check in eswitch lag check The function ice_lag_is_switchdev_running() is being called from outside of the LAG event handler code. This results in the lag->upper_netdev being NULL sometimes. To avoid a NULL-pointer dereference, there needs to be a check before it is dereferenced.

References

• https://git.kernel.org/stable/c/27591d926191e42b2332e4bad3bcd3a49def393b
• https://git.kernel.org/stable/c/5a5d64f0eec82076b2c09fee2195d640cfbe3379
• https://git.kernel.org/stable/c/245917d3c5ed7c6ae720302b64eac5c6f0c85177
• https://git.kernel.org/stable/c/3ce58b01ada408b372f15b7c992ed0519840e3cf