From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59784) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bFz5a-00007i-N2 for qemu-devel@nongnu.org; Thu, 23 Jun 2016 03:30:15 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bFz5Y-0001ue-Mv for qemu-devel@nongnu.org; Thu, 23 Jun 2016 03:30:13 -0400 From: Kevin Wolf Date: Thu, 23 Jun 2016 09:30:01 +0200 Message-Id: <1466667001-10167-1-git-send-email-kwolf@redhat.com> Subject: [Qemu-devel] [PATCH] block/qdev: Fix NULL access when using BB twice List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-block@nongnu.org Cc: kwolf@redhat.com, qemu-devel@nongnu.org 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 --- 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