Commit 7cef3d12 authored Jul 29, 2019 by Kevin Wolf

scsi-cd: Fix inserting read-only media in empty drive

scsi-disks decides whether it has a read-only device by looking at
whether the BlockBackend specified as drive=... is read-only. In the
case of an anonymous BlockBackend (with a node name specified in
drive=...), this is the read-only flag of the attached node. In the case
of an empty anonymous BlockBackend, it's always read-write because
nothing prevented it from being read-write.

This is a problem because scsi-cd would take write permissions on the
anonymous BlockBackend of an empty drive created without a drive=...
option. Using blockdev-insert-medium with a read-only node fails then
with the error message "Block node is read-only".

Fix scsi_realize() so that scsi-cd devices always take read-only
permissions on their BlockBackend instead.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1733920


Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>

parent 2b23f286

hw/scsi/scsi-disk.c

+8 −2

Original line number	Diff line number	Diff line
		@@ -2318,6 +2318,7 @@ static void scsi_disk_unit_attention_reported(SCSIDevice *dev)
		static void scsi_realize(SCSIDevice dev, Error *errp)
		{
		SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, dev);
		bool read_only;

		if (!s->qdev.conf.blk) {
		error_setg(errp, "drive property not set");
		@@ -2351,8 +2352,13 @@ static void scsi_realize(SCSIDevice dev, Error *errp)
		return;
		}
		}
		if (!blkconf_apply_backend_options(&dev->conf,
		blk_is_read_only(s->qdev.conf.blk),

		read_only = blk_is_read_only(s->qdev.conf.blk);
		if (dev->type == TYPE_ROM) {
		read_only = true;
		}

		if (!blkconf_apply_backend_options(&dev->conf, read_only,
		dev->type == TYPE_DISK, errp)) {
		return;
		}