In the Linux kernel, the following vulnerability has been resolved:

scsi: pm80xx: Fix array-index-out-of-of-bounds on rmmod

Since commit f7b705c238d1 ("scsi: pm80xx: Set phy_attached to zero when
device is gone") UBSAN reports:

  UBSAN: array-index-out-of-bounds in drivers/scsi/pm8001/pm8001_sas.c:786:17
  index 28 is out of range for type 'pm8001_phy [16]'

on rmmod when using an expander.

For a direct attached device, attached_phy contains the local phy id.
For a device behind an expander, attached_phy contains the remote phy
id, not the local phy id.

I.e. while pm8001_ha will have pm8001_ha->chip->n_phy local phys, for a
device behind an expander, attached_phy can be much larger than
pm8001_ha->chip->n_phy (depending on the amount of phys of the
expander).

E.g. on my system pm8001_ha has 8 phys with phy ids 0-7.  One of the
ports has an expander connected.  The expander has 31 phys with phy ids
0-30.

The pm8001_ha->phy array only contains the phys of the HBA.  It does not
contain the phys of the expander.  Thus, it is wrong to use attached_phy
to index the pm8001_ha->phy array for a device behind an expander.

Thus, we can only clear phy_attached for devices that are directly
attached.