On Wed, Feb 03, 2021 at 04:45:51PM +0000, Stefan Hajnoczi wrote:
On Tue, Feb 02, 2021 at 04:49:50PM +0100, Stefano Garzarella wrote: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.You could update the commit description so it's clear that input validation is missing and will be added in the next commit.
I'll do it. Thanks, Stefano
