Avihai Horon <avih...@nvidia.com> wrote: > As part of its error flow, vfio_vmstate_change() accesses > MigrationState->to_dst_file without any checks. This can cause a NULL > pointer dereference if the error flow is taken and > MigrationState->to_dst_file is not set. > > For example, this can happen if VM is started or stopped not during > migration and vfio_vmstate_change() error flow is taken, as > MigrationState->to_dst_file is not set at that time. > > Fix it by checking that MigrationState->to_dst_file is set before using > it. > > Fixes: 02a7e71b1e5b ("vfio: Add VM state change handler to know state of VM") > Signed-off-by: Avihai Horon <avih...@nvidia.com> > --- > hw/vfio/migration.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c > index 835608cd23..21e8f9d4d4 100644 > --- a/hw/vfio/migration.c > +++ b/hw/vfio/migration.c > @@ -744,7 +744,9 @@ static void vfio_vmstate_change(void *opaque, bool > running, RunState state) > */ > error_report("%s: Failed to set device state 0x%x", vbasedev->name, > (migration->device_state & mask) | value); > - qemu_file_set_error(migrate_get_current()->to_dst_file, ret); > + if (migrate_get_current()->to_dst_file) { > + qemu_file_set_error(migrate_get_current()->to_dst_file, ret); > + } > }
Reviewed-by: Juan Quintela <quint...@redhat.com> I mean that the change is right. But I am not so sure about using qemu_file_* operations outside of the migration_thread. I *think* that everything else that uses qemu_file_* functions is operating inside the migration_thread, and this one don't look like it. Furthermore, a fast look at qemu source, I can't see anyplace where we setup an error in a vmstate_change. Later, Juan. > vbasedev->migration->vm_running = running; > trace_vfio_vmstate_change(vbasedev->name, running, RunState_str(state),