On Wed, 9 Dec 2020 17:17:56 +0200 Paraschiv, Andra-Irina wrote: > > I agree that could be a problem, but here some considerations: > > - I checked some applications (qemu-guest-agent, ncat, iperf-vsock) and > > all use the same pattern: allocate memory, initialize all the > > sockaddr_vm to zero (to be sure to initialize the svm_zero), set the > > cid and port fields. > > So we should be safe, but of course it may not always be true. > > > > - For now the issue could affect only nested VMs. We introduced this > > support one year ago, so it's something new and maybe we don't cause > > too many problems. > > > > As an alternative, what about using 1 or 2 bytes from svm_zero[]? > > These must be set at zero, even if we only check the first byte in the > > kernel. > > Thanks for the follow-up info. > > We can also consider the "svm_zero" option and could use 2 bytes from > that field for "svm_flags", keeping the same "unsigned short" type.
Or use svm_zero as a gate for interpreting other fields? If svm_zero[0]* == something start checking the value of reserved1? * in practice the name can be unioned to something more palatable ;)
