On Wed, Oct 13, 2021 at 10:40:46AM +0100, Stefan Hajnoczi wrote:
> On Mon, Oct 11, 2021 at 10:10:47PM +0200, David Hildenbrand wrote:
> > We end up not copying the mmap_addr of all existing regions, resulting
> > in a SEGFAULT once we actually try to map/access anything within our
> > memory regions.
> >
> > Fixes: 875b9fd97b34 ("Support individual region unmap in libvhost-user")
> > Cc: qemu-sta...@nongnu.org
> > Cc: Michael S. Tsirkin <m...@redhat.com>
> > Cc: Raphael Norwitz <raphael.norw...@nutanix.com>
> > Cc: "Marc-André Lureau" <marcandre.lur...@redhat.com>
> > Cc: Stefan Hajnoczi <stefa...@redhat.com>
> > Cc: Paolo Bonzini <pbonz...@redhat.com>
> > Cc: Coiby Xu <coiby...@gmail.com>
> > Signed-off-by: David Hildenbrand <da...@redhat.com>
> > ---
> > subprojects/libvhost-user/libvhost-user.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/subprojects/libvhost-user/libvhost-user.c
> > b/subprojects/libvhost-user/libvhost-user.c
> > index bf09693255..787f4d2d4f 100644
> > --- a/subprojects/libvhost-user/libvhost-user.c
> > +++ b/subprojects/libvhost-user/libvhost-user.c
> > @@ -816,6 +816,7 @@ vu_rem_mem_reg(VuDev *dev, VhostUserMsg *vmsg) {
> > shadow_regions[j].gpa = dev->regions[i].gpa;
> > shadow_regions[j].size = dev->regions[i].size;
> > shadow_regions[j].qva = dev->regions[i].qva;
> > + shadow_regions[j].mmap_addr = dev->regions[i].mmap_addr;
> > shadow_regions[j].mmap_offset = dev->regions[i].mmap_offset;
> > j++;
> > } else {
>
> Raphael: Some questions about vu_rem_mem_reg():
>
> - What ensures that shadow_regions[VHOST_USER_MAX_RAM_SLOTS] is large
> enough? The add_mem_reg/set_mem_table code doesn't seem to check
> whether there is enough space in dev->regions[] before adding regions.
>
Correct - it does not check if there is enough space as is. I can add that.
> - What happens when the master populated dev->regions[] with multiple
> copies of the same region? dev->nregions is only decremented once and
> no longer accurately reflects the number of elements in
> dev->regions[].
That case is also not accounted for. I will add it.
>
> libvhost-user must not trust the vhost-user master since vhost-user
> needs to provide process isolation. Please add input validation.
>
Got it - let me start working on a series.
> Stefan
