From: Kameron Carr <[email protected]> Sent: Monday, October 19, 2026 4:10 PM > > Document that the guest must snapshot and validate the read and write > indices before using them to index into the ring buffer or to compute > the available space. > > Signed-off-by: Kameron Carr <[email protected]>
Reviewed-by: Michael Kelley <[email protected]> > --- > Documentation/virt/hyperv/coco.rst | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/Documentation/virt/hyperv/coco.rst > b/Documentation/virt/hyperv/coco.rst > index 3231e51..3e20249 100644 > --- a/Documentation/virt/hyperv/coco.rst > +++ b/Documentation/virt/hyperv/coco.rst > @@ -200,7 +200,10 @@ validation is performed. For messages passed from the > host > to the guest in a > VMBus ring buffer, the length of the message is validated, and the message is > copied into a temporary (encrypted) buffer for further validation and > processing. The copying adds a small amount of overhead, but is the only way > -to protect against a malicious host. See hv_pkt_iter_first(). > +to protect against a malicious host. See hv_pkt_iter_first(). Similarly, the > +ring buffer header is shared with the host, so the guest must snapshot and > +validate the read and write indices before using them to index into the ring > +buffer or to compute available space. > > Many drivers for VMBus devices have been "hardened" by adding code to fully > validate messages received over VMBus, instead of assuming that Hyper-V is > > -- > 2.45.4
