Re: [Qemu-devel] [Qemu-block] [PATCH] block/qdev: Fix NULL access when using BB twice

[Stefan Hajnoczi]

On Thu, Jun 23, 2016 at 09:30:01AM +0200, Kevin Wolf wrote:
> 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 <address@hidden>
> ---
>  hw/core/qdev-properties-system.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Reviewed-by: Stefan Hajnoczi <address@hidden>

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