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authorMichael S. Tsirkin <mst@redhat.com>2014-12-21 01:00:23 +0200
committerMichael S. Tsirkin <mst@redhat.com>2014-12-29 10:55:06 +0200
commit5d9a07b0de512b77bf28d2401e5fe3351f00a240 (patch)
tree1157d5803702f242d4b35268644ee48e20719307
parentb28e0506fafd9c987bba7a6a71ea02a37fcabdea (diff)
vhost: relax used address alignment
virtio 1.0 only requires used address to be 4 byte aligned, vhost required 8 bytes (size of vring_used_elem). Fix up vhost to match that. Additionally, while vhost correctly requires 8 byte alignment for log, it's unconnected to used ring: it's a consequence that log has u64 entries. Tweak code to make that clearer. Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
-rw-r--r--drivers/vhost/vhost.c10
1 files changed, 7 insertions, 3 deletions
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index ed71b5347a76..cb807d0ea498 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -713,9 +713,13 @@ long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp)
r = -EFAULT;
break;
}
- if ((a.avail_user_addr & (sizeof *vq->avail->ring - 1)) ||
- (a.used_user_addr & (sizeof *vq->used->ring - 1)) ||
- (a.log_guest_addr & (sizeof *vq->used->ring - 1))) {
+
+ /* Make sure it's safe to cast pointers to vring types. */
+ BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
+ BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
+ if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
+ (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
+ (a.log_guest_addr & (sizeof(u64) - 1))) {
r = -EINVAL;
break;
}