On Wed, Sep 11, 2019 at 02:33:16PM +0200, Michal Hocko wrote: > On Wed 11-09-19 08:25:03, Michael S. Tsirkin wrote: > > On Wed, Sep 11, 2019 at 02:16:28PM +0200, Michal Hocko wrote: > > > On Wed 11-09-19 08:10:00, 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> > > > > Acked-by: Jason Wang <jasowang@xxxxxxxxxx> > > > > Tested-by: Jason Wang <jasowang@xxxxxxxxxx> > > > > > > no need to mark fo stable? Other spectre fixes tend to be backported > > > even when the security implications are not really clear. The risk > > > should be low and better to be covered in case. > > > > This is not really a fix - more a defence in depth thing, > > quite similar to e.g. commit b3bbfb3fb5d25776b8e3f361d2eedaabb0b496cd > > x86: Introduce __uaccess_begin_nospec() and uaccess_try_nospec > > in scope. > > > > That one doesn't seem to be tagged for stable. Was it queued > > there in practice? > > not marked for stable but it went in. At least to 4.4. So I guess the answer is I don't know. If you feel it's justified, then sure, feel free to forward. -- MST
