On Tue, Feb 02, 2021 at 09:34:12AM +0000, Stefan Hajnoczi wrote:
On Thu, Jan 28, 2021 at 03:41:25PM +0100, Stefano Garzarella wrote:
+static void vdpasim_blk_work(struct work_struct *work)
+{
+ struct vdpasim *vdpasim = container_of(work, struct vdpasim, work);
+ u8 status = VIRTIO_BLK_S_OK;
+ int i;
+
+ spin_lock(&vdpasim->lock);
+
+ if (!(vdpasim->status & VIRTIO_CONFIG_S_DRIVER_OK))
+ goto out;
+
+ for (i = 0; i < VDPASIM_BLK_VQ_NUM; i++) {
+ struct vdpasim_virtqueue *vq = &vdpasim->vqs[i];
+
+ if (!vq->ready)
+ continue;
+
+ while (vringh_getdesc_iotlb(&vq->vring, &vq->out_iov,
+ &vq->in_iov, &vq->head,
+ GFP_ATOMIC) > 0) {
+ int write;
+
+ vq->in_iov.i = vq->in_iov.used - 1;
+ write = vringh_iov_push_iotlb(&vq->vring, &vq->in_iov,
+ &status, 1);
+ if (write <= 0)
+ break;
This code looks fragile:
1. Relying on unsigned underflow and the while loop in
vringh_iov_push_iotlb() to handle the case where in_iov.used == 0 is
risky and could break.
2. Does this assume that the last in_iov element has size 1? For
example, the guest driver may send a single "in" iovec with size 513
when reading 512 bytes (with an extra byte for the request status).
Please validate inputs fully, even in test/development code, because
it's likely to be copied by others when writing production code (or
deployed in production by unsuspecting users) :).
Perfectly agree on that, so I addressed these things, also following
your review on the previous version, on the next patch of this series:
"vdpa_sim_blk: implement ramdisk behaviour".
Do you think should I move these checks in this patch?
I did this to leave Max credit for this patch and add more code to
emulate a ramdisk in later patches.
Thanks,
Stefano
