CVE-2021-47060

In the Linux kernel, the following vulnerability has been resolved: KVM:
Stop looking for coalesced MMIO zones if the bus is destroyed Abort the
walk of coalesced MMIO zones if kvm_io_bus_unregister_dev() fails to
allocate memory for the new instance of the bus. If it can’t instantiate a
new bus, unregister_dev() destroys all devices except the target device.
But, it doesn’t tell the caller that it obliterated the bus and invoked the
destructor for all devices that were on the bus. In the coalesced MMIO
case, this can result in a deleted list entry dereference due to attempting
to continue iterating on coalesced_zones after future entries (in the walk)
have been deleted. Opportunistically add curly braces to the for-loop,
which encompasses many lines but sneaks by without braces due to the guts
being a single if statement.