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xen/intr: fix corruption of event channel table

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In xen_intr_release_isrc(), the isrc should only be removed if it is
assigned to a valid port.  This had been mitigated by using 0 for not
having a port, but this is actually corrupting the table.  Fix this bug
as modifying the code would cause this bug to manifest as kernel memory
corruption.  Similar issue for the vCPU bitmap masks.

The KASSERT() doesn't need lock protection.

Reviewed by: royger
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D30743
This commit is contained in:
Elliott Mitchell 2021-08-27 16:00:05 -07:00 committed by Roger Pau Monné
parent 0ebf9bb42d
commit 2b2415bafa
1 changed files with 15 additions and 12 deletions
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27
sys/x86/xen/xen_intr.c
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@ -350,23 +350,26 @@ static int
xen_intr_release_isrc(struct xenisrc *isrc)
{
mtx_lock(&xen_intr_isrc_lock);
KASSERT(isrc->xi_intsrc.is_handlers == 0,
("Release called, but xenisrc still in use"));
evtchn_mask_port(isrc->xi_port);
evtchn_clear_port(isrc->xi_port);
mtx_lock(&xen_intr_isrc_lock);
if (is_valid_evtchn(isrc->xi_port)) {
evtchn_mask_port(isrc->xi_port);
evtchn_clear_port(isrc->xi_port);
/* Rebind port to CPU 0. */
evtchn_cpu_mask_port(isrc->xi_cpu, isrc->xi_port);
evtchn_cpu_unmask_port(0, isrc->xi_port);
/* Rebind port to CPU 0. */
evtchn_cpu_mask_port(isrc->xi_cpu, isrc->xi_port);
evtchn_cpu_unmask_port(0, isrc->xi_port);
if (isrc->xi_close != 0 && is_valid_evtchn(isrc->xi_port)) {
struct evtchn_close close = { .port = isrc->xi_port };
if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close))
panic("EVTCHNOP_close failed");
if (isrc->xi_close != 0) {
struct evtchn_close close = { .port = isrc->xi_port };
if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close))
panic("EVTCHNOP_close failed");
}
xen_intr_port_to_isrc[isrc->xi_port] = NULL;
}
xen_intr_port_to_isrc[isrc->xi_port] = NULL;
isrc->xi_cpu = 0;
isrc->xi_type = EVTCHN_TYPE_UNBOUND;
isrc->xi_port = 0;