CVE-2023-52811

In the Linux kernel, the following vulnerability has been resolved: scsi:
ibmvfc: Remove BUG_ON in the case of an empty event pool In practice the
driver should never send more commands than are allocated to a queue’s
event pool. In the unlikely event that this happens, the code asserts a
BUG_ON, and in the case that the kernel is not configured to crash on panic
returns a junk event pointer from the empty event list causing things to
spiral from there. This BUG_ON is a historical artifact of the ibmvfc
driver first being upstreamed, and it is well known now that the use of
BUG_ON is bad practice except in the most unrecoverable scenario. There is
nothing about this scenario that prevents the driver from recovering and
carrying on. Remove the BUG_ON in question from ibmvfc_get_event() and
return a NULL pointer in the case of an empty event pool. Update all call
sites to ibmvfc_get_event() to check for a NULL pointer and perfrom the
appropriate failure or recovery action.