hw/virtio: fix crash in processing balloon stats

balloon_stats_get_all will iterate over guest stats upto the max
VIRTIO_BALLOON_S_NR value, calling visit_type_uint64 to populate
the QObject dict. The dict keys are obtained from the static
array balloon_stat_names which is VIRTIO_BALLOON_S_NR in size.

Unfortunately the way that array is declared results in any
unassigned stats getting a NULL name, which will then cause
visit_type_uint64 to trigger an assert in qobject_output_add_obj.

The balloon_stat_names array was fortunately fully populated with
names until recently:

  commit 0d2eeef77a33315187df8519491a900bde4a3d83
  Author: Bibo Mao <maobibo@loongson.cn>
  Date:   Mon Oct 28 10:38:09 2024 +0800

    linux-headers: Update to Linux v6.12-rc5

pulled a change to include/standard-headers/linux/virtio_balloon.h
which increased VIRTIO_BALLOON_S_NR by 6, and failed to add the new
names to balloon_stat_names.

This commit fills in the missing names, and uses a static assert to
guarantee that any future changes to VIRTIO_BALLOON_S_NR will cause
a build failure until balloon_stat_names is updated.

This problem was detected by the Cockpit Project's automated
integration tests on QEMU 9.2.0-rc1.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=2329448
Fixes: 0d2eeef77a3 ("linux-headers: Update to Linux v6.12-rc5")
Reported-by: Martin Pitt <mpitt@redhat.com>
Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <20241129135507.699030-2-berrange@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

0 files changed, 0 insertions, 0 deletions