Re: [Qemu-devel] [PATCH RFC v3 for-2.9 02/11] rbd: Fix to cleanly reject -drive without pool or image

[Jeff Cody <jcody@redhat.com>]

On Mon, Mar 27, 2017 at 08:58:28PM +0200, Markus Armbruster wrote:
> Markus Armbruster <armbru@redhat.com> writes:
> 
> > Max Reitz <mreitz@redhat.com> writes:
> >
> >> On 27.03.2017 18:10, Max Reitz wrote:
> >>> On 27.03.2017 15:26, Markus Armbruster wrote:
> >>>> qemu_rbd_open() neglects to check pool and image are present.
> >>>> Reproducer:
> >>>>
> >>>>     $ qemu-system-x86_64 -nodefaults -drive if=none,driver=rbd,pool=p
> >>>>     Segmentation fault (core dumped)
> >>>>     $ qemu-system-x86_64 -nodefaults -drive if=none,driver=rbd,image=i
> >>>>     qemu-system-x86_64: -drive if=none,driver=rbd,image=i: error opening pool (null)
> >>>>
> >>>> Doesn't affect -drive with file=..., because qemu_rbd_parse_filename()
> >>>> always sets both pool and image.
> >>>>
> >>>> Doesn't affect -blockdev, because pool and image are mandatory in the
> >>>> QAPI schema.
> >>>>
> >>>> Fix by adding the missing checks.
> >>>>
> >>>> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> >>>> Reviewed-by: Eric Blake <eblake@redhat.com>
> >>>> ---
> >>>>  block/rbd.c | 10 +++++++---
> >>>>  1 file changed, 7 insertions(+), 3 deletions(-)
> >>> 
> >>> Reviewed-by: Max Reitz <mreitz@redhat.com>
> >>
> >> That said, don't we have a similar issue with qemu_rbd_create()? It too
> >> doesn't check whether those options are given but I guess they're just
> >> as mandatory.
> >
> > Looks like it.  I'll try to stick a fix into v4.
> 
> Hmm, ignorant question: how can I reach qemu_rbd_create() without going
> through qemu_rbd_parse_filename()?

You can't -- commit c7cacb3e7 forces qemu_rbd_create() to call
qemu_rbd_parse_filename().  And in qemu_rbd_parse_filename(), it will
complain if pool is not provided (and that is what causes the abort, not the
missing image parameter).  So I think we are safe, but a nicer error message
for a missing 'image' parameter might be nice anyway.