[libvirt PATCH] vircgroupv2: fix virCgroupV2DenyDevice

The original logic is incorrect. We would delete the device entry from eBPF map only if the newval would be same as current val in the map. In case that the device was allowed only as read-only but later we remove all permissions for that device it would remain in the table with empty values. The old code would still deny the device but it's not working as intended. Instead we will update the value in advance. If the updated value is 0 it means that we are removing all permissions so it should be removed from the map, otherwise we will update the value in map. Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1810356 Signed-off-by: Pavel Hrdina <phrdina(a)redhat.com&gt; --- src/util/vircgroupv2.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/src/util/vircgroupv2.c b/src/util/vircgroupv2.c index 2b32f614e4..40cfa20376 100644 --- a/src/util/vircgroupv2.c +++ b/src/util/vircgroupv2.c @@ -1796,7 +1796,9 @@ virCgroupV2DenyDevice(virCgroupPtr group, return 0; } - if (newval == val) { + val = val & ~newval; + + if (val == 0) { if (virBPFDeleteElem(group->unified.devices.mapfd, &key) < 0) { virReportSystemError(errno, "%s", _("failed to remove device from BPF cgroup map")); @@ -1804,7 +1806,6 @@ virCgroupV2DenyDevice(virCgroupPtr group, } group->unified.devices.count--; } else { - val ^= val & newval; if (virBPFUpdateElem(group->unified.devices.mapfd, &key, &val) < 0) { virReportSystemError(errno, "%s", _("failed to update device in BPF cgroup map")); -- 2.28.0