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| author | Brian Foley <brian.foley@arm.com> | 2012-09-24 14:33:42 +0100 |
|---|---|---|
| committer | Rusty Russell <rusty@rustcorp.com.au> | 2012-09-28 15:05:16 +0930 |
| commit | d78b519f6b945aef6202bbb5b56f928572e15165 (patch) | |
| tree | b055dd93fb446914a908ebec0829ce89df9b53c0 /drivers/virtio/virtio_mmio.c | |
| parent | 3850d29fc40f3494a3e9c3aac45b6afe53526449 (diff) | |
| download | linux-d78b519f6b945aef6202bbb5b56f928572e15165.tar.gz linux-d78b519f6b945aef6202bbb5b56f928572e15165.tar.bz2 linux-d78b519f6b945aef6202bbb5b56f928572e15165.zip | |
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/virtio_mmio.c')
| -rw-r--r-- | drivers/virtio/virtio_mmio.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c index 09edeecd42a5..6b1b7e184939 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)); |