Re: [PATCH net] vhost: Use kzalloc() to allocate vhost_msg_node

[Michael S. Tsirkin]

On Fri, Apr 27, 2018 at 06:11:31PM +0200, Dmitry Vyukov wrote:
> On Fri, Apr 27, 2018 at 6:05 PM, Michael S. Tsirkin <mst@xxxxxxxxxx> wrote:
> > On Fri, Apr 27, 2018 at 11:45:02AM -0400, Kevin Easton wrote:
> >> The struct vhost_msg within struct vhost_msg_node is copied to userspace,
> >> so it should be allocated with kzalloc() to ensure all structure padding
> >> is zeroed.
> >>
> >> Signed-off-by: Kevin Easton <kevin@xxxxxxxxxxx>
> >> Reported-by: syzbot+87cfa083e727a224754b@xxxxxxxxxxxxxxxxxxxxxxxxx
> >
> > Does it help if a patch naming the padding is applied,
> > and then we init just the relevant field?
> > Just curious.
> 
> Yes, it would help.

I think it's slightly better that way then. node has a lot of internal
stuff we don't care to init. Would you mind taking my patch and building
on top of that then?

> >> ---
> >>  drivers/vhost/vhost.c | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> >> index f3bd8e9..1b84dcff 100644
> >> --- a/drivers/vhost/vhost.c
> >> +++ b/drivers/vhost/vhost.c
> >> @@ -2339,7 +2339,7 @@ EXPORT_SYMBOL_GPL(vhost_disable_notify);
> >>  /* Create a new message. */
> >>  struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type)
> >>  {
> >> -     struct vhost_msg_node *node = kmalloc(sizeof *node, GFP_KERNEL);
> >> +     struct vhost_msg_node *node = kzalloc(sizeof *node, GFP_KERNEL);
> >>       if (!node)
> >>               return NULL;
> >>       node->vq = vq;
> >> --
> >> 2.8.1
> >
> > --
> > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@xxxxxxxxxxxxxxxxx
> > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/20180427185501-mutt-send-email-mst%40kernel.org.
> > For more options, visit https://groups.google.com/d/optout.