On Fri, Nov 19, 2021 at 11:10 PM Halil Pasic <pasic@xxxxxxxxxxxxx> wrote: > > On Wed, 27 Oct 2021 10:21:04 +0800 > Jason Wang <jasowang@xxxxxxxxxx> wrote: > > > This patch validate the used buffer length provided by the device > > before trying to use it. This is done by record the in buffer length > > in a new field in desc_state structure during virtqueue_add(), then we > > can fail the virtqueue_get_buf() when we find the device is trying to > > give us a used buffer length which is greater than the in buffer > > length. > > > > Since some drivers have already done the validation by themselves, > > this patch tries to makes the core validation optional. For the driver > > that doesn't want the validation, it can set the > > suppress_used_validation to be true (which could be overridden by > > force_used_validation module parameter). To be more efficient, a > > dedicate array is used for storing the validate used length, this > > helps to eliminate the cache stress if validation is done by the > > driver. > > > > Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx> > > Hi Jason! > > Our CI has detected, that virtio-vsock became unusable with this > patch on s390x. I didn't test on x86 yet. The guest kernel says > something like: > vmw_vsock_virtio_transport virtio1: tx: used len 44 is larger than in buflen 0 > > Did you, or anybody else, see something like this on platforms other that > s390x? Adding Stefan and Stefano. I think it should be a common issue, looking at vhost_vsock_handle_tx_kick(), it did: len += sizeof(pkt->hdr); vhost_add_used(vq, head, len); which looks like a violation of the spec since it's TX. > > I had a quick look at this code, and I speculate that it probably > uncovers a pre-existig bug, rather than introducing a new one. I agree. > > If somebody is already working on this please reach out to me. AFAIK, no. I think the plan is to fix both the device and drive side (but I'm not sure we need a new feature for this if we stick to the validation). Thanks > > Regards, > Halil > _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
