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virtio-net: fix use after unmap/free for sg #1379

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virtio-net: fix use after unmap/free for sg #1379

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39 changes: 32 additions & 7 deletions hw/net/virtio-net.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1142,10 +1142,13 @@ static ssize_t virtio_net_receive_rcu(NetClientState *nc, const uint8_t *buf,
VirtIONet *n = qemu_get_nic_opaque(nc);
VirtIONetQueue *q = virtio_net_get_subqueue(nc);
VirtIODevice *vdev = VIRTIO_DEVICE(n);
VirtQueueElement *elems[VIRTQUEUE_MAX_SIZE];
size_t lens[VIRTQUEUE_MAX_SIZE];
struct iovec mhdr_sg[VIRTQUEUE_MAX_SIZE];
struct virtio_net_hdr_mrg_rxbuf mhdr;
unsigned mhdr_cnt = 0;
size_t offset, i, guest_offset;
size_t offset, i, guest_offset, j;
ssize_t err;

if (!virtio_net_can_receive(nc)) {
return -1;
Expand All @@ -1168,6 +1171,12 @@ static ssize_t virtio_net_receive_rcu(NetClientState *nc, const uint8_t *buf,

total = 0;

if (i == VIRTQUEUE_MAX_SIZE) {
virtio_error(vdev, "virtio-net unexpected long buffer chain");
err = size;
goto err;
}

elem = virtqueue_pop(q->rx_vq, sizeof(VirtQueueElement));
if (!elem) {
if (i) {
Expand All @@ -1179,15 +1188,17 @@ static ssize_t virtio_net_receive_rcu(NetClientState *nc, const uint8_t *buf,
n->guest_hdr_len, n->host_hdr_len,
vdev->guest_features);
}
return -1;
err = -1;
goto err;
}

if (elem->in_num < 1) {
virtio_error(vdev,
"virtio-net receive queue contains no in buffers");
virtqueue_detach_element(q->rx_vq, elem, 0);
g_free(elem);
return -1;
err = -1;
goto err;
}

sg = elem->in_sg;
Expand Down Expand Up @@ -1219,12 +1230,13 @@ static ssize_t virtio_net_receive_rcu(NetClientState *nc, const uint8_t *buf,
if (!n->mergeable_rx_bufs && offset < size) {
virtqueue_unpop(q->rx_vq, elem, total);
g_free(elem);
return size;
err = size;
goto err;
}

/* signal other side */
virtqueue_fill(q->rx_vq, elem, total, i++);
g_free(elem);
elems[i] = elem;
lens[i] = total;
i++;
}

if (mhdr_cnt) {
Expand All @@ -1234,10 +1246,23 @@ static ssize_t virtio_net_receive_rcu(NetClientState *nc, const uint8_t *buf,
&mhdr.num_buffers, sizeof mhdr.num_buffers);
}

for (j = 0; j < i; j++) {
/* signal other side */
virtqueue_fill(q->rx_vq, elems[j], lens[j], j);
g_free(elems[j]);
}

virtqueue_flush(q->rx_vq, i);
virtio_notify(vdev, q->rx_vq);

return size;

err:
for (j = 0; j < i; j++) {
g_free(elems[j]);
}

return err;
}

static ssize_t virtio_net_receive(NetClientState *nc, const uint8_t *buf,
Expand Down