On Mon, Sep 09, 2019 at 03:19:55PM +0800, Jason Wang wrote: > > On 2019/9/8 下午7:05, Michael S. Tsirkin wrote: > > iovec addresses coming from vhost are assumed to be > > pre-validated, but in fact can be speculated to a value > > out of range. > > > > Userspace address are later validated with array_index_nospec so we can > > be sure kernel info does not leak through these addresses, but vhost > > must also not leak userspace info outside the allowed memory table to > > guests. > > > > Following the defence in depth principle, make sure > > the address is not validated out of node range. > > > > Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx> > > --- > > drivers/vhost/vhost.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > > index 5dc174ac8cac..0ee375fb7145 100644 > > --- a/drivers/vhost/vhost.c > > +++ b/drivers/vhost/vhost.c > > @@ -2072,7 +2072,9 @@ static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len, > > size = node->size - addr + node->start; > > _iov->iov_len = min((u64)len - s, size); > > _iov->iov_base = (void __user *)(unsigned long) > > - (node->userspace_addr + addr - node->start); > > + (node->userspace_addr + > > + array_index_nospec(addr - node->start, > > + node->size)); > > s += size; > > addr += size; > > ++ret; > > > I've tried this on Kaby Lake smap off metadata acceleration off using > testpmd (virtio-user) + vhost_net. I don't see obvious performance > difference with TX PPS. > > Thanks Should I push this to Linus right now then? It's a security thing so maybe we better do it ASAP ... what's your opinion? -- MST
