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authorBrian Foley <brian.foley@arm.com>2012-09-24 14:33:42 +0100
committerRusty Russell <rusty@rustcorp.com.au>2012-09-28 15:05:16 +0930
commitd78b519f6b945aef6202bbb5b56f928572e15165 (patch)
treeb055dd93fb446914a908ebec0829ce89df9b53c0 /drivers/virtio
parent3850d29fc40f3494a3e9c3aac45b6afe53526449 (diff)
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op-kernel-dev-d78b519f6b945aef6202bbb5b56f928572e15165.tar.gz
virtio_mmio: Don't attempt to create empty virtqueues
If a virtio device reports a QueueNumMax of 0, vring_new_virtqueue() doesn't check this, and thanks to an unsigned (i < num - 1) loop guard, scribbles over memory when initialising the free list. Avoid by not trying to create zero-descriptor queues, as there's no way to do any I/O with one. Signed-off-by: Brian Foley <brian.foley@arm.com> Signed-off-by: Pawel Moll <pawel.moll@arm.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'drivers/virtio')
-rw-r--r--drivers/virtio/virtio_mmio.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index 09edeec..6b1b7e1 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -331,6 +331,16 @@ static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned index,
* and two rings (which makes it "alignment_size * 2")
*/
info->num = readl(vm_dev->base + VIRTIO_MMIO_QUEUE_NUM_MAX);
+
+ /* If the device reports a 0 entry queue, we won't be able to
+ * use it to perform I/O, and vring_new_virtqueue() can't create
+ * empty queues anyway, so don't bother to set up the device.
+ */
+ if (info->num == 0) {
+ err = -ENOENT;
+ goto error_alloc_pages;
+ }
+
while (1) {
size = PAGE_ALIGN(vring_size(info->num,
VIRTIO_MMIO_VRING_ALIGN));
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