Commit 3850d29f authored Sep 24, 2012 by Brian Foley Committed by Rusty Russell Sep 28, 2012

virtio_mmio: fix off by one error allocating queue



vm_setup_vq fails to allow VirtQueues needing only 2 pages of
storage, as it should. Found with a kernel using 64kB pages, but
can be provoked if a virtio device reports QueueNumMax where the
descriptor table and available ring fit in one page, and the used
ring on the second (<= 227 descriptors with 4kB pages and <= 3640
with 64kB pages.)

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>

parent 74a74b37

drivers/virtio/virtio_mmio.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -334,8 +334,8 @@ static struct virtqueue vm_setup_vq(struct virtio_device vdev, unsigned index,
		while (1) {
		size = PAGE_ALIGN(vring_size(info->num,
		VIRTIO_MMIO_VRING_ALIGN));
		/* Already smallest possible allocation? */
		if (size <= VIRTIO_MMIO_VRING_ALIGN * 2) {
		/* Did the last iter shrink the queue below minimum size? */
		if (size < VIRTIO_MMIO_VRING_ALIGN * 2) {
		err = -ENOMEM;
		goto error_alloc_pages;
		}