On Fri, Jul 19, 2024, Mirsad Todorovac wrote:
> Hi, all,
>
> While building stable tree version of 6.10, the following error occurred:
>
> In line 1421 defines:
>
> 1421 evtchn_port_t port, *ports;
>
> The ports becomes &port in line 1470, but neither port nor *ports is assigned a value
> until line 1486 where port is used:
>
> 1485 if (sched_poll.nr_ports == 1)
> 1486 → vcpu->arch.xen.poll_evtchn = port;
>
> The visual inspection proves that the compiler is again right (GCC 12.3.0).
Nope, the compiler is wrong. If sched_poll.nr_ports > 0, then kvm_read_guest_virt()
will fill ports[sched_poll.nr_ports]. If kvm_read_guest_virt() fails to do so,
it will return an error and the above code will never be reached.
if (kvm_read_guest_virt(vcpu, (gva_t)sched_poll.ports, ports,
sched_poll.nr_ports * sizeof(*ports), &e)) {
*r = -EFAULT;
return true;
}
