BlockBackend has only a single pointer to its guest device, so it makes sure that only a single guest device is attached to it. device-add returns an error if you try to attach a second device to a BB. In order to make the error message nicer, -device that manually connects to a if=none block device get a different message than -drive that implicitly creates a guest device. The if=... option is stored in DriveInfo.
However, since blockdev-add exists, not every BlockBackend has a DriveInfo any more. Check that it exists before we dereference it. QMP reproducer resulting in a segfault: {"execute":"blockdev-add","arguments":{"options":{"id":"disk","driver":"file","filename":"/tmp/test.img"}}} {"execute":"device_add","arguments":{"driver":"virtio-blk-pci","drive":"disk"}} {"execute":"device_add","arguments":{"driver":"virtio-blk-pci","drive":"disk"}} Signed-off-by: Kevin Wolf <kw...@redhat.com> --- hw/core/qdev-properties-system.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c index 623be94..c5cc9cf 100644 --- a/hw/core/qdev-properties-system.c +++ b/hw/core/qdev-properties-system.c @@ -91,7 +91,7 @@ static void parse_drive(DeviceState *dev, const char *str, void **ptr, if (blk_attach_dev(blk, dev) < 0) { DriveInfo *dinfo = blk_legacy_dinfo(blk); - if (dinfo->type != IF_NONE) { + if (dinfo && dinfo->type != IF_NONE) { error_setg(errp, "Drive '%s' is already in use because " "it has been automatically connected to another " "device (did you need 'if=none' in the drive options?)", -- 1.8.3.1