On Fri, Apr 27, 2018 at 09:07:56PM -0400, Kevin Easton wrote: > On Fri, Apr 27, 2018 at 07:05:45PM +0300, Michael S. Tsirkin 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 <ke...@guarana.org> > > > Reported-by: syzbot+87cfa083e727a2247...@syzkaller.appspotmail.com > > > > Does it help if a patch naming the padding is applied, > > and then we init just the relevant field? > > Just curious. > > No, I don't believe that is sufficient to fix the problem.
Scratch that, somehow I missed the "..and then we init just the relevant field" part, sorry. There's still the padding after the vhost_iotlb_msg to consider. It's named in the union but I don't think that's guaranteed to be initialised when the iotlb member of the union is used to initialise things. > I didn't name the padding in my original patch because I wasn't sure > if the padding actually exists on 32 bit architectures? This might still be a concern, too? At the end of the day, zeroing 96 bytes (the full size of vhost_msg_node) is pretty quick. - Kevin